Human Anatomy and Physiology Answers

CHAPTER 1. Scope of anatomy and physiology, basic terminologies used in this subject.
(description
of the body as such planes and terminologies)
SHORT ESSAYS (2M)
1.Define Anatomy and Physiology?

Answer: Anatomy is (study of structure of body) the branch of science that studies the physical structure
of a human body. Physiology is (study of functioning of living things) the branch of biology that deals
with the internal workings of living things, including functions such as metabolism, respiration, and
reproduction.
2.Define anatomical position, sagittal plane?

Answer: The erect position of the body with the face directed forward, the arms at the side, and the palms
of the hands facing forward, used as a reference in describing the relation of body parts to one another.
A sagittal plane is an anatomical plane which divides the body into right and left parts. The plane may be
in the centre of the body and split it into two halves (mid-sagittal) or away from the midline and split it into
unequal parts (para-sagittal).
3.Mention the descriptive terms used in Anatomy?

Answer:
• Median plane-the vertical plane which divides the body into left and right halves
• Paramedian-any plane parallel to the median or sagittal plane
• Coronal plane-any vertical plane at right angles to the median plane
• Transverse plane-any plane at right angles to both median and coronal planes
• Oblique-any other plane than transverse, coronal, sagittal, etc
• Medial-closer to the midline of the body
• Lateral-further from the midline of the body
• Anterior-nearer the front surface of the body
• Posterior-nearer the rear surface of the body
CHAPTER 2. STRUCTURE OF CELL-ITS COMPONENTS AND THEIR FUNCTIONS.
SHORT ESSAY (5M)
1.Explain the structure and functions of cell membrane.

Answer:
Structure of the Plasma Membrane
The basic structural framework of the
plasma membrane is the lipid bilayer,
two back-to-back layers made up of three
types of lipid molecules—phospholipids,
cholesterol, and glycolipids. About 75%
of the membrane lipids are
phospholipids, lipids that contain
phosphorus. Present in smaller amounts
are cholesterol (about 20%), glycolipids
(about 5%), lipids with attached
carbohydrate groups. The bilayer
arrangement occurs because they have both polar and nonpolar parts. In phospholipids, the polar part is the
phosphate containing “head,” which is hydrophilic (hydro- water; philic- loving). The nonpolar parts are
the two-long fatty acid “tails,” which are hydrophobic (water loving) hydrocarbon chains. In this way, the
heads face a watery fluid on either side—cytosol on the inside and extracellular fluid on the outside. The
hydrophobic fatty acid tails in each half of the bilayer point toward one another, forming a nonpolar,
hydrophobic region in the membrane’s interior.
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Function of cell membrane
• Branched carbohydrate molecules attached to the outside of some membrane protein molecules give
the cell its immunological identity.
• They can act as specific receptors (recognition sites) for hormones and other chemical messengers.
• Some are enzymes.
• Some are involved in transport across the membrane.
2. Describe the functions of Golgi complex and mitochondria.

Answer:
Golgi Complex
The Golgi apparatus consists of stacks of closely folded flattened membranous sacs. It is present in all cells
but is larger in those that synthesise and export proteins. The proteins move from the endoplasmic reticulum
to the Golgi apparatus where they are ‘packaged’ into membrane-bound vesicles. The vesicles are stored
and, when needed, they move to the plasma membrane and fuse with it. The contents are expelled (secreted)
from the cell. This process is called exocytosis
• Modifies, sorts, packages, and transports proteins received from the rough ER.
• Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid;
forms membrane vesicles that ferry new molecules to the plasma membrane; forms transport
vesicles that carry molecules to other organelles, such as lysosomes.
Mitochondria
Mitochondria are membranous, sausage-shaped structures in the cytoplasm, sometimes described as the
‘power house’ of the cell. They are central to aerobic respiration, the processes by which chemical energy
is made available in the cell. This is in the form of ATP, which releases energy when the cell breaks it
down. Synthesis of ATP is most efficient in the final stages of aerobic respiration, a process which requires
oxygen
• Generate ATP through reactions of aerobic cellular respiration.
3. Mention different cell organelles with their functions.

Answer:
▪ LYSOSOME: Produces enzymes to destroy bacteria. Breaks down food particles.
▪ RIBOSOME: Produces proteins.
▪ CYTOSKELETON: Internal support system for cell. Acts as a framework
• GOLGI BODY: Modifies, sorts, packages, and transports proteins received from the rough ER.
Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid;
forms membrane vesicles that ferry new molecules to the plasma membrane; forms transport
vesicles that carry molecules to other organelles, such as lysosomes.
▪ ENDOPLASMIC RETICULUM: Transport system inside cell.
▪ ROUGH ENDOPLASMIC RETICULUM: Has ribosome on its surface and produces proteins
▪ SMOOTH ENDOPLASMIC RETICULUM: Does not have ribosomes on its surface and produces
lipids
▪ NUCLEUS: Control centre of cell.
▪ FLAGELLUM: Long tail-like structure for cell locomotion.
• MITOCHONDRIA: Generate ATP through reactions of aerobic cellular respiration.
▪ CYTOPLASM: Supports all cell organelles.
▪ CELL MEMBRANE: Semi-permeable to control enter and exit of materials.
▪ NUCLEOLUS: Produces ribosomes.
▪ CHROMOSOMES: Genetic material in nucleus.
4. Distinguish between rough and smooth endoplasmic reticulum (ER). What are the
functions of ER?
Answer:
Endoplasmic reticulum is an extensive series of interconnecting membranous canals in the cytoplasm.
There are two types: smooth and rough. Smooth ER synthesises lipids and steroid hormones, and is also
associated with the detoxification of some drugs. Some of the lipids are used to replace and repair the
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plasma membrane and membranes of organelles. Rough ER is studded with ribosomes. These are the site
of synthesis of proteins, some of which are ‘exported’ from cells, i.e. enzymes and hormones that leave the
parent cell by exocytosis to be used by cells elsewhere.
Functions
• Rough ER synthesizes glycoproteins and phospholipids that are transferred into cellular organelles,
inserted into the plasma membrane, or secreted during exocytosis.
• Smooth ER synthesizes fatty acids and steroids, such as estrogens and testosterone; inactivates or
detoxifies drugs and other potentially harmful substances; removes the phosphate group from
glucose-6-phosphate; and stores and releases calcium ions that trigger contraction in muscle cells.
5.Discuss the structure and functions of ribosomes and lysosomes.

Answer: Ribosomes are tiny granules composed of RNA and protein. They synthesise proteins from amino
acids, using RNA as the template. When present in free units or in small clusters in the cytoplasm, the
ribosomes make proteins for use within the cell. These include the enzymes required for metabolism.
Metabolic pathways consist of a series of steps, each driven by a specific enzyme. Ribosomes are also
found on the outer surface of the nuclear envelope and rough endoplasmic reticulum where they
manufacture proteins for export from the cell.
Lysosomes are small membranous vesicles pinched off from the Golgi apparatus. They contain a variety
of enzymes involved in breaking down fragments of organelles and large molecules (e.g. RNA, DNA,
carbohydrates, proteins) inside the cell into smaller particles that are either recycled, or extruded from the
cell as waste material. Lysosomes in white blood cells contain enzymes that digest foreign material such as
microbes.
6.Draw a neat labeled diagram of cell and write the functions of nucleus.
Answer:
Functions of nucleus
1. Controls cellular structure.
2. Directs cellular activities.
3. Produces ribosomes in nucleoli.
SHORT ANSWERS (2M)
1. Write the functions of mitochondria.

Answer: Mitochondria are membranous, sausage-shaped structures in the cytoplasm, sometimes described
as the ‘power house’ of the cell. They are central to aerobic respiration, the processes by which chemical
energy is made available in the cell. This is in the form of ATP, which releases energy when the cell breaks
it down. Synthesis of ATP is most efficient in the final stages of aerobic respiration, a process which
requires oxygen.
• Generate ATP through reactions of aerobic cellular respiration
2. Explain the functions of plasma membrane.

Answer:
• Branched carbohydrate molecules attached to the outside of some membrane protein molecules give
the cell its immunological identity.
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• They can act as specific receptors (recognition sites) for hormones and other chemical messengers.
• Some are enzymes.
• Some are involved in transport across the membrane.
3. Why are mitochondria referred to as “power houses” of the cell?

Answer: They are central to aerobic respiration, the processes by which chemical energy is made available
in the cell. This is in the form of ATP, which releases energy when the cell breaks it down. Synthesis of
ATP is most efficient in the final stages of aerobic respiration, a process which requires oxygen.
4. Why the nucleus is called the control centre of the cell? Write its functions.
Answer:
Function of nucleus
1. Controls cellular structure.
2. Directs cellular activities.
3. Produces ribosomes in nucleoli
5. Describe mitochondria
Answer: Mitochondria are membranous, sausage-shaped structures in the cytoplasm, sometimes described
as the ‘power house’ of the cell. They are central to aerobic respiration, the processes by which chemical
energy is made available in the cell. This is in the form of ATP, which releases energy when the cell breaks
it down. Synthesis of ATP is most efficient in the final stages of aerobic respiration, a process which
requires oxygen.
6. Lysosomes and chromosomes

Answer: Lysosomes are small membranous vesicles pinched off from the Golgi apparatus. They contain
a variety of enzymes involved in breaking down fragments of organelles and large molecules (e.g. RNA,
DNA, carbohydrates, proteins) inside the cell into smaller particles that are either recycled, or extruded
from the cell as waste material. Lysosomes in white blood cells contain enzymes that digest foreign material
such as microbes. In the nucleus of each cell, the DNA molecule is packaged into thread-like structures
called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins
called histones that support its structure.
7. Mention the components of a cell.

Answer:
CHAPTER 3. ELEMENTARY TISSUES OF THE HUMAN BODY
SHORT ESSAYS (5M)
1.Classify tissues with examples.

Answer:
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• Epithelial: Is made of cells arranged in a continuous sheet with one or more layers, has apical &
basal surfaces.
o A basement membrane is the attachment between the basal surface of the cell & the
underlying connective tissue.
o Two types of epithelial tissues: (1) Covering & lining epithelia and (2) Glandular
Epithelium.
o The number of cell layers & the shape of the cells in the top layer can classify epithelium.
▪ Simple Epithelium - one cell layer
▪ Stratified epithelium - two or more cell layers
▪ Pseudostratified Columnar Epithelium - When cells of an epithelial tissue are all
anchored to the basement Membrane but not all cells reach the apical surface.
▪ Glandular Epithelium – (1) Endocrine: Release hormones directly into the blood
stream and (2) Exocrine - Secrete into ducts.
• Connective: contains many different cell types including: fibroblasts, macrophages, mast cells, and
adipocytes. Connective Tissue Matrix is made of two materials: ground substance - proteins and
polysaccharides, fiber – reticular, collagen and elastic.
Classification of Connective Tissue:

o Loose Connective - fibers & many cell types in gelatinous matrix, found in skin, &
surrounding blood vessels, nerves, and organs.
o Dense Connective - Bundles of parallel collagen fibers& fibroblasts, found in tendons&
ligaments.
o Cartilage - Cartilage is made of collagen & elastin fibers embedded in a matrix glycoprotein
& cells called chondrocytes, which was found in small spaces.
o Cartilage has three subtypes:
▪ Hyaline cartilage – Weakest, most abundant type, Found at end of long bones, &
structures like the ear and nose,
▪ Elastic cartilage- maintains shape, branching elastic fibers distinguish it from
hyaline and
▪ Fibrous Cartilage - Strongest type, has dense collagen & little matrix, found in
pelvis, skull & vertebral discs.
• Muscle: is divided into 3 categories, skeletal, cardiac and smooth.
o Skeletal Muscle – voluntary, striated, striations perpendicular to the muscle fibers and it is
mainly found attached to bones.
o Cardiac Muscle – involuntary, striated, branched and has intercalated discs
o Smooth Muscle – involuntary, nonstriated, spindle shaped and is found in blood vessels &
the GI tract.
• Nervous tissue detects changes in a variety of conditions inside and outside the body and responds
by generating action potentials (nerve impulses) that activate muscular contractions and glandular
secretions.
2.Explain the differences among skeletal, smooth and cardiac muscles.

Answer:
Skeletal muscle
This type is described as skeletal because it forms those muscles that move the bones (of the skeleton),
striated because striations (stripes) can be seen on microscopic examination and voluntary as it is under
conscious control. Although most skeletal muscle moves bones, the diaphragm is made from this type of
muscle to accommodate a degree of voluntary control in breathing. These fibres (cells) are cylindrical,
contain several nuclei and can be up to 35 cm long. Skeletal muscle contraction is stimulated by motor
nerve impulses originating in the brain or spinal cord and ending at the neuromuscular junction.
Smooth muscle
Smooth muscle is also described as non-striated, visceral or involuntary. It does not have striations and is
not under conscious control. Some smooth muscle has the intrinsic ability to initiate its own contractions
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(automaticity), e.g. peristalsis. It is innervated by the autonomic nervous system. Additionally, autonomic
nerve impulses, some hormones and local metabolites stimulate its contraction. A degree of muscle tone is
always present, meaning that smooth muscle is only completely relaxed for short periods. Contraction of
smooth muscle is slower and more sustained than skeletal muscle. It is found in the walls of hollow organs:
• regulating the diameter of blood vessels and parts of the respiratory tract
• propelling contents along, e.g. the ureters, ducts of glands and the alimentary tract
• expelling contents of the urinary bladder and uterus.
Cardiac muscle
This is only found only in the heart wall. It is not under conscious control but, when viewed under a
microscope, cross-stripes (striations) characteristic of skeletal muscle can be seen. Each fibre (cell) has a
nucleus and one or more branches. The ends of the cells and their branches are in very close contact with
the ends and branches of adjacent cells. Microscopically these ‘joints’, or intercalated discs, appear as lines
that are thicker and darker than the ordinary cross-stripes. This arrangement gives cardiac muscle the
appearance of a sheet of muscle rather than a very large number of individual fibres.
3.Define cartilage, mention its type. Give the description, function and examples of each of them.
Answer: Cartilage is firmer than other connective tissues. The cells (chondrocytes) are sparse and lie
embedded in matrix reinforced by collagen and elastic fibres. There are three types: hyaline cartilage,
fibrocartilage and elastic fibrocartilage.
Hyaline cartilage
Hyaline cartilage is a smooth bluish-white tissue. The chondrocytes are arranged in small groups within
cell nests and the matrix is solid and smooth. Hyaline cartilage provides flexibility, support and smooth
surfaces for movement at joints. It is found:
• on the ends of long bones that form joints
• forming the costal cartilages, which attach the ribs to the sternum
• forming part of the larynx, trachea and bronchi.
Fibro cartilage
This consists of dense masses of white collagen fibres in a matrix similar to that of hyaline cartilage with
the cells widely dispersed. It is a tough, slightly flexible, supporting tissue found:
• as pads between the bodies of the vertebrae, the intervertebral discs
• between the articulating surfaces of the bones of the knee joint, called semilunar cartilages
• on the rim of the bony sockets of the hip and shoulder joints, deepening the cavities without restricting
movement.
Elastic fibrocartilage
This flexible tissue consists of yellow elastic fibres lying in a solid matrix with chondrocytes lying between
the fibres. It provides support and maintains shape of, e.g. the pinna or lobe of the ear, the epiglottis and
part of the tunica media of blood vessel walls.
4.Differenciate between loose and dense connective tissues.

Answer:
Dense connective tissue
This contains more fibres and fewer cells than loose connective tissue.
➢ Fibrous tissue
This tissue is made up mainly of closely packed bundles of collagen fibres with very little matrix. Fibrocytes
(old and inactive fibroblasts) are few in number and lie in rows between the bundles of fibres. Fibrous tissue
is found:
• forming ligaments, which bind bones together
• as an outer protective covering for bone, called periosteum
• as an outer protective covering of some organs, e.g. the kidneys, lymph nodes and the brain
• forming muscle sheaths, called muscle fascia, which extend beyond the muscle to become the tendon that
attaches the muscle to bone.
➢ Elastic tissue
Elastic tissue is capable of considerable extension and recoil. There are few cells and the matrix consists
mainly of masses of elastic fibres secreted by fibroblasts. It is found in organs where stretching or alteration
of shape is required, e.g. in large blood vessel walls, the trachea and bronchi, and the lungs.
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Loose connective tissue
This is the most generalised type of connective tissue. The matrix is semisolid with many fibroblasts and
some fat cells (adipocytes), mast cells and macrophages widely separated by elastic and collagen fibres. It
is found in almost every part of the body, providing elasticity and tensile strength. It connects and supports
other tissues, for example:
• under the skin
• between muscles
• supporting blood vessels and nerves
• in the alimentary canal
• in glands supporting secretory cells.
5.Describe the different types of epithelial tissues with examples.

Answer: Simple epithelia & Stratified epithelia
Squamous (pavement) epithelium
This is composed of a single layer of flattened cells. The cells fit closely together like flat stones, forming
a thin and very smooth membrane across which diffusion occurs easily. It forms the lining of the following
structures:
➢ heart – where it is known as endocardium
➢ blood vessels where it is also known
➢ lymph vessels as endothelium
➢ alveoli of the lungs
➢ lining the collecting ducts of nephrons in the kidneys
Cuboidal epithelium
This consists of cube-shaped cells fitting closely together lying on a basement membrane. It forms the
kidney tubules and is found in some glands such as the thyroid. Cuboidal epithelium is actively involved
in secretion, absorption and/or excretion.
Columnar epithelium
This is formed by a single layer of cells, rectangular in shape, on a basement membrane. It lines many
organs and often has adaptations that make it well suited to a specific function. The lining of the stomach
is formed from simple columnar epithelium without surface structures. The free surface of the columnar
epithelium lining the small intestine is covered with microvilli.
Stratified epithelia
Stratified epithelia consist of several layers of cells of various shapes. Continual cell division in the lower
(basal) layers pushes cells above nearer and nearer to the surface, where they are shed. Basement
membranes are usually absent. The main function of stratified epithelium is to protect underlying structures
from mechanical wear and tear. There are two main types: stratified squamous and transitional.
Stratified squamous epithelium
This is composed of several layers of cells. In the deepest layers the cells are mainly columnar and, as they
grow towards the surface, they become flattened and are then shed.
Keratinised stratified epithelium. This is found on dry surfaces subjected to wear and tear, i.e. skin, hair
and nails. The surface layer consists of dead epithelial cells that have lost their nuclei and contain the protein
keratin. This form a tough, relatively waterproof protective layer that prevents drying of the live cells
underneath. The surface layer of skin is rubbed off and is replaced from below.
Non-keratinised stratified epithelium. This protects moist surfaces subjected to wear and tear, and prevents
them from drying out, e.g. the conjunctiva of the eyes, the lining of the mouth, the pharynx, the oesophagus
and the vagina.
Transitional epithelium
This is composed of several layers of pear-shaped cells. It lines several parts of the urinary tract including
the bladder and allows for stretching as the bladder fills.
6.Explain the structure and functions of neuron.

Answer:
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Each neurone consists of a cell body and its
processes, one axon and many dendrites.
Neurones are commonly referred to as nerve
cells. Bundles of axons bound together are
called nerves. Neurones cannot divide, and for
survival they need a continuous supply of
oxygen and glucose. Unlike many other cells,
neurones can synthesise chemical energy
(ATP) only from glucose.
Neurones generate and transmit electrical
impulses called action potentials. The initial
strength of the impulse is maintained
throughout the length of the neurone. Some neurones initiate nerve impulses while others act as ‘relay
stations’ where impulses are passed on and sometimes redirected. Nerve impulses can be initiated in
response to stimuli from:
• outside the body, e.g. touch, light waves
• inside the body, e.g. a change in the concentration of carbon dioxide in the blood alters respiration; a
thought may result in voluntary movement.
SHORT ANSWERS (2M)

1. Classify muscular tissue with examples.
Answer: Muscle: is divided into 3 categories, skeletal, cardiac and smooth.
o Skeletal Muscle – voluntary, striated, striations perpendicular to the muscle fibers and it is
mainly found attached to bones.
o Cardiac Muscle – involuntary, striated, branched and has intercalated discs
o Smooth Muscle – involuntary, nonstriated, spindle shaped and is found in blood vessels &
the GI tract.
2. Classify connective tissue with examples.

Answer: Connective: contains many different cell types including: fibroblasts, macrophages, mast cells,
and adipocytes. Connective Tissue Matrix is made of two materials: ground substance - proteins and
polysaccharides, fiber – reticular, collagen and elastic.
Classification of Connective Tissue:
o Loose Connective - fibers & many cell types in gelatinous matrix, found in skin, &
surrounding blood vessels, nerves, and organs.
o Dense Connective - Bundles of parallel collagen fibers& fibroblasts, found in tendons&
ligaments.
o Cartilage - Cartilage is made of collagen & elastin fibers embedded in a matrix glycoprotein
& cells called chondrocytes, which was found in small spaces.
o Cartilage has three subtypes:
▪ Hyaline cartilage – Weakest, most abundant type, Found at end of long bones, &
structures like the ear and nose,
▪ Elastic cartilage- maintains shape, branching elastic fibers distinguish it from
hyaline and
▪ Fibrous Cartilage - Strongest type, has dense collagen & little matrix, found in
pelvis, skull & vertebral discs.
3. Draw a neat labelled diagram of neuron.
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Answer:
4. Classify simple epithelium with examples.

Answer: Squamous (pavement) epithelium or Simple epithelium
This is composed of a single layer of flattened cells. The cells fit closely together like flat stones, forming
a thin and very smooth membrane across which diffusion occurs easily. It forms the lining of the following
structures:
➢ heart – where it is known as endocardium
➢ blood vessels where it is also known
➢ lymph vessels as endothelium
➢ alveoli of the lungs
➢ lining the collecting ducts of nephrons in the kidneys
Cuboidal epithelium
This consists of cube-shaped cells fitting closely together lying on a basement membrane. It forms the
kidney tubules and is found in some glands such as the thyroid. Cuboidal epithelium is actively involved
in secretion, absorption and/or excretion.
Columnar epithelium
This is formed by a single layer of cells, rectangular in shape, on a basement membrane. It lines many
organs and often has adaptations that make it well suited to a specific function. The lining of the stomach
is formed from simple columnar epithelium without surface structures. The free surface of the columnar
epithelium lining the small intestine is covered with microvilli.
5. Classify compound epithelium with examples.
Answer: Stratified epithelia or Compound epithelium
Stratified epithelia consist of several layers of cells of various shapes. Continual cell division in the lower
(basal) layers pushes cells above nearer and nearer to the surface, where they are shed. Basement
membranes are usually absent. The main function of stratified epithelium is to protect underlying structures
from mechanical wear and tear. There are two main types: stratified squamous and transitional.
Stratified squamous epithelium
This is composed of several layers of cells. In the deepest layers the cells are mainly columnar and, as they
grow towards the surface, they become flattened and are then shed.
Keratinised stratified epithelium. This is found on dry surfaces subjected to wear and tear, i.e. skin, hair
and nails. The surface layer consists of dead epithelial cells that have lost their nuclei and contain the protein
keratin. This form a tough, relatively waterproof protective layer that prevents drying of the live cells
underneath. The surface layer of skin is rubbed off and is replaced from below.
Non-keratinised stratified epithelium. This protects moist surfaces subjected to wear and tear, and prevents
them from drying out, e.g. the conjunctiva of the eyes, the lining of the mouth, the pharynx, the oesophagus
and the vagina.
Transitional epithelium
6. Write the general characteristics of epithelial tissue.
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Answer: This tissue type covers the body and lines cavities, hollow organs and tubes. It is also found in
glands. The structure of epithelium is closely related to its functions, which include:
• protection of underlying structures from, for example, dehydration, chemical and mechanical damage
• secretion
• absorption.
The cells are very closely packed and the intercellular substance, the matrix, is minimal. The cells usually
lie on a basement membrane, which is an inert connective tissue made by the epithelial cells themselves.
Epithelial tissue may be:
• simple: a single layer of cells
• stratified: several layers of cells.
7. Write the location and functions of Transitional epithelium.
Answer: Transitional epithelium
CHAPTER 4. OSSEOUS SYSTEM
SHORT ESSAYS (5M)
1. Classify joints with examples

Answer:
2. Explain the Haversian canal system of bone.

Answer: Haversian canals a series of microscopic tubes in the outermost region of bone called cortical
bone that allow blood vessels and nerves to travel through them. Each haversian canal generally contains
one or two capillaries and nerve fibres. The channels are formed by concentric layers called lamellae. The
haversian canals surround blood vessels and nerve cells throughout bones and communicate with bone
cells (contained in spaces within the dense bone matrix called lacunae) through connections
called canaliculi. This unique arrangement is conducive to mineral salt deposits and storage which
gives bone tissue its strength.
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In mature compact bone most of the individual lamellae form concentric rings around larger longitudinal
canals within the bone tissue. These canals are called haversian canals. Haversian canals are contained
within osteons, which are typically arranged along the long axis of the bone in parallel to the surface. The
canals and the surrounding lamellae (8-15) form the functional unit, called a haversian system or osteon.
3. Write the composition and functions of bone.
Answer: Function of bone
I. Providing the body framework
II. Giving attachment to muscles and tendons
III. Allowing movement of the body as a whole and of parts of the body, by forming joints that are
moved by muscles
IV. Forming the boundaries of the cranial, thoracic and pelvic cavities, and protecting the organs they
contain
V. Haemopoiesis, the production of blood cells in red bone marrow
VI. Mineral storage, especially calcium phosphate the mineral reservoir within bone is essential for
maintenance of blood calcium levels, which must be tightly controlled.
Composition of bone
Osteoblasts
These bone-forming cells are responsible for the deposition of both inorganic salts and osteoid in bone
tissue.
They are therefore present at sites where bone is growing, repairing or remodelling, e.g.:
a) In the deeper layers of periosteum
b) In the centres of ossification of immature bone
c) At the ends of the diaphysis adjacent to the epiphyseal cartilages of long bones
d) At the site of a fracture.
As they deposit new bone tissue around themselves, they eventually become trapped in tiny pockets
(lacunae) in the growing bone, and differentiate into osteocytes.
Osteocytes
These are mature bone cells that monitor and maintain bone tissue, and are nourished by tissue fluid in the
canaliculi that radiate from the central canals.
Osteoclasts
These cells break down bone, releasing calcium and phosphate. They are very large cells with up to 50
nuclei, which have formed from the fusion of many monocytes. The continuous remodelling of healthy
bone tissue is the result of balanced activity of the bone’s osteoblast and osteoclast populations. Osteoclasts
are found in areas of the bone where there is active growth, repair or remodelling,
e.g.:
a) Under the periosteum, maintaining bone shape during growth and to remove excess callus formed
during healing of fractures.
b) Round the walls of the medullary canal during growth and to canalise callus during healing.
4. Describe angular and special movements of joints.

Answer:
Special movements
a) Elevation is an upward movement of a part of the body, such as closing the mouth at the
temporomandibular joint (between the mandible and temporal bone) to elevate the mandible.
b) Depression is a downward movement of a part of the body, such as opening the mouth to depress
the mandible or returning shrugged shoulders to the anatomical position to depress the scapula.
c) Protraction is a movement of a part of the body anteriorly in the transverse plane.
d) Retraction is a movement of a protracted part of the body back to the anatomical position.
e) Inversion is movement of the sole medially at the intertarsal joints (between the tarsal).
f) Eversion is a movement of the sole laterally at the intertarsal joints.
g) Dorsiflexion refers to bending of the foot at the ankle or talocrural joint in the direction of the
dorsum. Dorsiflexion occurs when you stand on your heels.
h) Plantar flexion involves bending of the foot at the ankle joint in the direction of the plantar or
inferior surface, as when you elevate your body by standing on your toes.
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i) Supination is a movement of the forearm at the proximal and distal radioulnar joints in which the
palm is turned anteriorly.
j) Pronation is a movement of the forearm at the proximal and distal radioulnar joints in which the
distal end of the radius crosses over the distal end of the ulna and the palm is turned posteriorly.
k) Opposition is the movement of the thumb at the carpometacarpal joint in which the thumb moves
across the palm to touch the tips of the fingers on the same hand.
Angular movements (Increase or decrease in the angle between bones)

a) Flexion - Decrease in the angle between articulating bones, usually in the sagittal plane.
b) Lateral flexion - Movement of the trunk in the frontal plane.
c) Extension - Increase in the angle between articulating bones, usually in the sagittal plane.
d) Hyperextension - Extension beyond the anatomical position.
e) Abduction - Movement of a bone away from the midline, usually in the frontal plane.
f) Adduction - Movement of a bone toward the midline, usually in the frontal plane.
g) Circumduction - Flexion, abduction, extension, and adduction in succession, in which the distal
end of a body part moves in a circle.
5. What is synovial joint? Explain its types with examples.

Answer:
Synovial joints are characterised by the presence of a space or capsule between the articulating bones. The
ends of the bones are held close together by a sleeve of fibrous tissue, and lubricated with a small amount
of fluid. Synovial joints are the most moveable of the body.
Synovial Joint Types (structural Description Example
classification)
Planar Articulated surfaces are flat or slightly Intercarpal, Intertarsal, Sternocostal
curved (between sternum and the second–
seventh pairs of ribs), and
vertebrocostal joints
Hinge Convex surface fits into a concave Knee (modified hinge), extension.
surface elbow, ankle, and interphalangeal joints
Pivot Rounded or pointed surface fits into a Atlanto-axial and radioulnar joints.
ring.
formed partly by bone and partly by a
ligament.
Condyloid Oval-shaped projection fits into an Radiocarpal and metacarpophalangeal
oval-shaped depression. joints.
Saddle Articular surface of one bone is saddle- Carpometarcarpal joint between
shaped, and the articular surface of the trapezium and thumb.
other bone “sits” in the saddle.
Ball-and-socket Ball-like surface fits into a cuplike Shoulder and hip joints.
depression.
6.Classify axial skeletal system with examples.

Answer:
In the human skeleton, axial skeletal consists of 80 bones and is composed of six parts; the skull bones,
the ossicles of the middle ear, the hyoid bone, the rib cage, sternum and the vertebral column.
Cranial Bones Facial Bones Auditory Ossicles Vertebral Column Thoracic Cage
Parietal (2) Maxilla (2) Malleus (2) Cervical vertebrae (7) Sternum (1)
Temporal (2) Zygomatic (2) Incus (2) Thoracic vertebrae (12) Ribs (24)
Ethmoid (1) Mandible (1) Stapes (2) Lumbar vertebrae (5)
Sphenoid (1) Nasal (2) Sacrum (1)

Occipital (1) Platine (2) Coccyx (1)
ELNAZ. Z 12
Frontal (1) Inferior nasal concha (2)
Lacrimal (2)
Vomer (1)
7.Classify appendicular skeletal system with examples.

Answer:
Pectoral girdles Upper Extremity Pelvic Girdle Lower Extremity
Clavicle (2) Humerus (2) Coxal, innominate, or Femur (2)
hip bones (2)
Scapula (2) Radius (2) Tibia (2)
Ulna (2) Fibula (2)
Carpals (16) Patella (2)
Metacarpals (10) Tarsals (14)
Phalanges (28) Metatarsals (10)
Phalanges (28)
8.Classify bones on the basis of shape along with examples.

Answer:
1. Long "Long bones" are longer than they are wide, • Femur (leg bone)
Bones i.e. length > diameter. • Tibia (leg bone)
Long bones are usually somewhat curved -
• Fibula (leg bone)
contributing to their mechanical strength.
• Humerus (arm bone)
• Ulna (arm bone)
• Radius (arm bone)
2. Short "Short bones" can be approximately cube- • Scaphoid bone (wrist bone)
Bones shaped, • Lunate bone (wrist bone)
i.e. length is similar to
• Hamate bone (wrist bone)
width/depth/diameter. and other wrist bones = carpal bones
• Cuboid bone (ankle bone)
• First Cuniform bone (ankle bone)
• Second Cuniform bone (ankle bone)
and other ankle bones = tarsal bones
3. Flat "Flat bones" have a thin shape and, in some • Cranial bones (protecting the brain) e.g.
Bones cases, provide mechanical protection to soft o Frontal bone
tissues beneath or enclosed by the flat bone o Parietal bones
e.g. cranial bones that protect the brain.
Flat bones also have extensive surfaces for • Sternum (protecting organs in the thorax)
muscle attachments e.g. scapulae (shoulder) • Ribs (protecting organs in the thorax)
bones. • Scapulae (shoulder blades).
4. Irregular "Irregular bones" have complicated shapes • Atlas bone

Bones that cannot be classified as "long", "short" or • Axis bone
"flat". Their shapes are due to the functions and other vertebrae
they fulfill within the body e.g. providing • Hyoid bone
major mechanical support for the body yet
also protecting the spinal cord (in the case of • Sphenoid bone
the vertebrae). • Zygomatic bones
and other facial bones.
ELNAZ. Z 13
5. Sesamoid "Sesamoid bones" develop in some tendons Only one type of sesamoid bone is present in all
in locations where there is considerable normal human skeletons so has a name. That is
Bones
the patella (singular), patellae (plural). Patellae are
friction, tension, and physical stress. also called "kneecaps". Complete human skeletons
include 2 of these, one in each leg.
SHORT ANSWERS (2M)

1. Name synovial joints
Answer: Planar, Hinge, Pivot, Condyloid, Saddle and Ball-and-socket
2. Classify bone marrow and functions.
Answer:
Bone marrow can be 1 of 2 types, red or yellow, depending on whether it consists of mainly hematopoietic
(red coloured) tissue or fatty ( yellow coloured) tissue. Bone marrow functions primarily to
produce blood cells and to store fat.
Red marrow is found mainly in the flat bones, such as the hip bone, sternum (breast) bone, skull, ribs,
vertebrae, and shoulder blades, as well as in the metaphyseal and epiphyseal ends of the long bones, such
as the femur, tibia, and humerus, where the bone is cancellous or spongy.
Yellow marrow is found in the hollow interior of the diaphyseal portion or the shaft of long bones. By the
time a person reaches old age, nearly all of the red marrow is replaced by yellow marrow. However, the
yellow marrow can revert to red if there is increased demand for red blood cells, such as in instances of
blood loss.
3. Define an articulation.
Answer: Articulation is the connection made between bones in the body which link the skeletal system
into a functional whole.
4. Write the histology of bone

Answer: Bone is a strong and durable type of connective tissue. Its major constituent (65%) is a mixture
of calcium salts, mainly calcium phosphate. This inorganic matrix gives bone great hardness, but on its
own would be brittle and prone to shattering. The remaining third is organic material, called osteoid, which
is composed mainly of collagen. Collagen is very strong and gives bone slight flexibility. The cellular
component of bone contributes less than 2% of bone mass.
Bone cells
There are three types of bone cell:
• Osteoblast
• Ostecyte
• Osteoclast
5. Name the bones of cranium

Answer: 1 frontal bone, 2 parietal bones, 2 temporal bones, 1 occipital bone, 1 sphenoid bone & 1 ethmoid
bone
6. Name the bone cells

Answer: Bone cells
There are three types of bone cell:
• Osteoblast: These bone-forming cells are responsible for the deposition of both inorganic salts and
osteoid in bone tissue. They are therefore present at sites where bone is growing, repairing or
remodelling.
• Ostecyte: These are mature bone cells that monitor and maintain bone tissue, and are nourished by
tissue fluid in the canaliculi that radiate from the central canals.
• Osteoclast: These cells break down bone, releasing calcium and phosphate. They are very large
cells with up to 50 nuclei, which have formed from the fusion of many monocytes.
ELNAZ. Z 14
7. Name the bones of the face.
Answer: 2 zygomatic (cheek) bones, 1 maxilla, 2 nasal bones, 2 lacrimal bones, 1 vomer, 2 palatine bones,
2 inferior conchae & 1 mandible.
8. Mention the bones of the upper limb.

Answer: Humerus, Ulna, Radius, Carpal (wrist) bones (There are eight carpal bones arranged in two rows
of four. From outside inwards they are proximal row: scaphoid, lunate, triquetrum, pisiform and distal row:
trapezium, trapezoid, capitate, hamate), Metacarpal bones (bones of the hand) and Phalanges (finger bones).
9. Mention the bones of the lower limb.

Answer: Femur (thigh bone), Tibia (shin bone), Fibula, Patella (knee cap), Tarsal (ankle) bones,
Metatarsals (bones of the foot) and Phalanges (toe bones).
10. Name the bones of the vertebral column.

Answer: Cervical vertebrae (7), Thoracic vertebrae (12), Lumbar vertebrae (5), Sacrum (1) and Coccyx
(1).
11.Write the functions of bone.

Answer: Function of bone
I. Providing the body framework
II. Giving attachment to muscles and tendons
III. Allowing movement of the body as a whole and of parts of the body, by forming joints that are
moved by muscles
IV. Forming the boundaries of the cranial, thoracic and pelvic cavities, and protecting the organs they
contain
V. Haemopoiesis, the production of blood cells in red bone marrow
VI. Mineral storage, especially calcium phosphate the mineral reservoir within bone is essential for
maintenance of blood calcium levels, which must be tightly controlled.
CHAPTER 5. HAEMOPOIETIC SYSTEM
LONG ESSAYS (10Marks)

1. Describe the constituents of blood and their functions.
Answer: PLASMA
When formed elements are removed from blood, a straw coloured liquid called blood plasma is left.
OTHER SOLUTES Inorganic salts. Positively charges ions(cations) include Na +,K+,Ca+,Mg2+;

(1.5%) Negatively charged ions(anions) include Cl-,HPO42-,SO42-,HCO3-. Help
ELECTROLYTES maintain osmotic pressure and plays essential roles in function of cells.
NUTRIENTS Products of digestion pass into blood for distribution to all body cells. Includes
amino acids(from proteins), glucose(from carbohydrates), fatty acids and
glycerol(from triglycerides), vitamins and minerals.
GASES Oxygen, Carbon dioxide and Nitrogen. More O2 is associated with
hemoglobin inside red blood cells; more CO2 is dissolved in plasma. N2 is
present but has no known functions in the body.
REGULATORY Enzymes, produces by body cells, catalyze chemical reactions. Hormones,
SUBSTANCES produced by endocrine glands, regulate metabolism, growth and development.
Vitamins are cofactors for enzymatic reactions.
WASTE PRODUCTS Most are breakdown products of protein metabolism and are carried by blood
to organs of excretion. Include urea, uric acid, creatine, creatinine, bilirubin
and ammonia.
ELNAZ. Z 15
WATER (91.5%) Liquid portion of blood. Acts as solvent and suspending medium for
components of blood; absorbs, transports and releases heat.
PLASMA PROTEIN Exert colloid osmotic pressure, which helps maintain water balance between
(7.0%) blood and tissues and regulates blood volume.
ALBUMIN Smallest and most numerous blood plasma proteins; produces by liver.
Transports proteins for several steroid hormones and for fatty acids.
GLOBULINS Produces by liver and plasma cells, which develop from B lymphocytes.
Antibodies help attack viruses and bacteria. Alpha and beta globulins transport
iron, lipids and fat soluble vitamin.
FIBRINOGEN Produces by liver. Plays essential role in blood clotting.
FORMED ELEMENTS FUNCTIONS

Red Blood Cells(RBCs) Hemoglobin within RBCs transports most of the oxygen and part of carbon
or Erythrocytes dioxide in the blood.
White Blood Combat pathogen and other foreign substances that enter the body.
Cells(WBCs) or
Leukocytes
Granular Leukocytes Phagocytosis. Destruction of bacteria with lysozymes, defensins and strong
Neutrophiles oxidants, such as superoxide anion, hydrogen peroxide, and hypochlorite
anion.
Eosinophils Eliminates parasites, such as worms which are too big to be phagocytosed;
phagocytes antigen-antibody complexes & combat the effects of histamine in
allergic reactions.
Basophils Liberate heparin, histamine and serotonin in allergic reactions that intensify
the overall inflammatory response.
Agranular Leukocytes Medium immune response, including antigen-antibody reactions. B cells
Lymphocytes(T cells, B develop into plasma cells, which secrete antibodies, T cells attack invading
cells & natural killer viruses, cancer cells, and transplanted tissue cells. Natural killer calls attach
cells) a wide variety of infectious microbes and certain spontaneously arising tumor
cells.
Monocytes Acts on the hypothalamus, causing the rise in body temperature with
microbial infections; stimulates the production of some globulins by the liver;
enhances the production of activated T-lymphocytes; Phagocytosis.
Platelets(Thrombocytes) Form platelet plug in homeostasis; release chemicals that promote vascular
spasm and blood clotting.
ELNAZ. Z 16
2.Mention coagulation factors and write the mechanism of blood coagulation
Answer: coagulation factors
• I Fibrinogen
• II Prothrombin
• III Tissue factor (thromboplastin)
• IV Calcium (Ca2+)
• V Labile factor, proaccelerin, Ac-globulin
• VII Stable factor, proconvertin
• VIII Antihaemophilic globulin (AHG), antihaemophilic factor A
• IX Christmas factor, plasma thromboplastin component (PTA), antihaemophilic factor B
• X Stuart Prower factor
• XI Plasma thromboplastin antecedent (PTA), antihaemophilic factor C
• XII Hageman factor
• XIII Fibrin stabilising factor
• Vitamin K is essential for synthesis of
factors II, VII, IX and X.
Stages of blood coagulation
This is a complex process that also involves a
positive feedback system. The factors involved
are listed above. These clotting factors activate
each other in a specific order, eventually
resulting in the formation of prothrombin
activator, which is the first step in the final
common pathway. Prothrombin activates the
enzyme thrombin, which converts inactive
fibrinogen to insoluble threads of fibrin. As
clotting proceeds, the platelet plug is
progressively stabilised by increasing amounts
of fibrin laid down in a three-dimensional
meshwork within it. The maturing blood clot
ELNAZ. Z 17
traps blood cells and other plasma proteins including plasminogen (which will eventually destroy the clot),
and is much stronger than the rapidly formed platelet plug.
The final common pathway can be initiated by two processes which often occur together: the extrinsic and
intrinsic pathways. The extrinsic pathway is activated rapidly (within seconds) following tissue damage.
Damaged tissue releases a complex of chemicals called thromboplastin or tissue factor, which initiates
coagulation. The intrinsic pathway is slower (3–6 minutes) and is triggered when blood comes into contact
with damaged blood vessel lining (endothelium). After a time the clot shrinks (retracts) because the
platelets contract, squeezing out serum, a clear sticky fluid that consists of plasma from which clotting
factors have been removed. Clot shrinkage pulls the edges of the damaged vessel together, reducing blood
loss and closing off the hole in the vessel wall.
3. Describe the process of Erythropoiesis and factors required or influencing erythropoiesis.

Answer: Erythropoiesis the production of RBCs, starts in the
red bone marrow with a precursor cell called a proerythroblast.
The proerythroblast divides several times, producing cells that
begin to synthesize haemoglobin. Ultimately, a cell near the end
of the development sequence ejects its nucleus and becomes a
reticulocyte. Loss of the nucleus causes the center of the cell to
indent, producing the red blood cell’s distinctive biconcave
shape. Reticulocytes retain some mitochondria, ribosomes, and
endoplasmic reticulum. They pass from red bone marrow into
the bloodstream by squeezing between the endothelial cells of
blood capillaries. Reticulocytes develop into mature red blood
cells within 1 to 2 days after their release from red bone marrow.
Normally, erythropoiesis and red blood cell destruction proceed
at roughly the same pace. If the oxygen-carrying capacity of the
blood falls because erythropoiesis is not keeping up with RBC
destruction, a negative feedback system steps up RBC
production. The controlled condition is the amount of oxygen
delivered to body tissues. Cellular oxygen deficiency, called
hypoxia, may occur if too little oxygen enters the blood. For
example, the lower oxygen content of air at high altitudes reduces the amount of oxygen in the blood.
Oxygen delivery may also fall due to anemia, which has many causes: Lack of iron, lack of certain amino
acids, and lack of vitamin B12 are but a few. Circulatory problems that reduce blood flow to tissues may
also reduce oxygen delivery. Whatever the cause, hypoxia stimulates the kidneys to step up the release of
erythropoietin, which speeds the development of proerythroblasts into reticulocytes in the red bone marrow.
As the number of circulating RBCs increases, more oxygen can be delivered to body tissues.
SHORT ESSAYS (5M)

1. Describe the ABO system of blood grouping.
Answer
ELNAZ. Z 18
2. Describe the structure and functions of platelets.
Answer:
These are very small discs, 2–4 μm in diameter, derived from the cytoplasm of megakaryocytes in red bone
marrow. Although they have no nucleus, their cytoplasm is packed with granules containing a variety of
substances that promote blood clotting, which causes haemostasis (cessation of bleeding). The normal
blood platelet count is between 200 × 109/L and 350 × 109/L (200 000–350 000/mm3). The mechanisms
that regulate platelet numbers are not fully understood, but the hormone thrombopoeitin from the liver
stimulates platelet production. The life span of platelets is between 8 and 11 days and those not used in
haemostasis are destroyed by macrophages, mainly in the spleen. About a third of platelets are stored within
the spleen rather than in the circulation; this is an emergency store that can be released as required to control
excessive bleeding.
Function-Form platelet plug in hemostasis; release chemicals that promote vascular spasm and blood
clotting.
3. Write any eight functions of blood.

Answer: Blood has three main functions: transport, protection and regulation.
Transport
Blood transports the following substances:
• Gases, namely oxygen (O2) and carbon dioxide (CO2), between the lungs and rest of the body
• Nutrients from the digestive tract and storage sites to the rest of the body
• Waste products to be detoxified or removed by the liver and kidneys
• Hormones from the glands in which they are produced to their target cells
• Heat to the skin so as to help regulate body temperature
Protection
Blood has several roles in inflammation:
• Leukocytes, or white blood cells, destroy invading microorganisms and cancer cells
• Antibodies and other proteins destroy pathogenic substances
• Platelet factors initiate blood clotting and help minimise blood loss
Regulation
Blood helps regulate:
• pH by interacting with acids and bases
• Water balance by transferring water to and from tissues
ELNAZ. Z 19
4. What is anaemia? Explain its types
Answer: Anaemia is the inability of the blood to carry enough oxygen to meet body needs. Usually this is
because there are low levels of haemoglobin in the blood, but sometimes it is due to production of faulty
haemoglobin.
• Iron deficiency anemia. This is the most common type of anemia worldwide. Iron deficiency anemia
is caused by a shortage of iron in your body. Your bone marrow needs iron to make hemoglobin.
Without adequate iron, your body can't produce enough hemoglobin for red blood cells.
• Vitamin deficiency anemia. In addition to iron, your body needs folate and vitamin B-12 to produce
enough healthy red blood cells. A diet lacking in these and other key nutrients can cause decreased
red blood cell production.
• Anemia of chronic disease. Certain diseases — such as cancer, HIV/AIDS, rheumatoid arthritis,
kidney disease, Crohn's disease and other chronic inflammatory diseases — can interfere with the
production of red blood cells.
• Aplastic anemia. This rare, life-threatening anemia occurs when your body doesn't produce enough
red blood cells. Causes of aplastic anemia include infections, certain medicines, autoimmune diseases
and exposure to toxic chemicals.
• Anemias associated with bone marrow disease. A variety of diseases, such as leukemia and
myelofibrosis, can cause anemia by affecting blood production in your bone marrow. The effects of
these types of cancer and cancer-like disorders vary from mild to life-threatening.
• Hemolytic anemias. This group of anemias develops when red blood cells are destroyed faster than
bone marrow can replace them. Certain blood diseases increase red blood cell destruction. You can
inherit a hemolytic anemia, or you can develop it later in life.
• Sickle cell anemia. This inherited and sometimes serious condition is an inherited hemolytic anemia.
It's caused by a defective form of hemoglobin that forces red blood cells to assume an abnormal
crescent (sickle) shape. These irregular blood cells die prematurely, resulting in a chronic shortage of
red blood cells.
• Other anemias. There are several other forms of anemia, such as thalassemia and malarial anemia.
5. Classify leucocytes. Mention its functions.

Answer:
Cells(WBCs) or
Leukocytes
Granular Leukocytes Phagocytosis. Destruction of bacteria with lysozymes, defensins and strong
Neutrophiles oxidants, such as superoxide anion, hydrogen peroxide, and hypochlorite
anion.
Eosinophils Eliminates parasites, such as worms which are too big to be phagocytosed;
phagocytes antigen-antibody complexes & combat the effects of histamine in
allergic reactions.
Basophils Liberate heparin, histamine and serotonin in allergic reactions that intensify
the overall inflammatory response.
Agranular Medium immune response, including antigen-antibody reactions. B cells
Leukocytes develop into plasma cells, which secrete antibodies, T cells attack invading
Lymphocytes(T cells, viruses, cancer cells, and transplanted tissue cells. Natural killer calls attach a
B cells & natural killer wide variety of infectious microbes and certain spontaneously arising tumor
cells) cells.
ELNAZ. Z 20
Monocytes Acts on the hypothalamus, causing the rise in body temperature with microbial
infections; stimulates the production of some globulins by the liver; enhances
the production of activated T-lymphocytes; Phagocytosis.
6. Explain the factors influencing the blood coagulation.

Answer: coagulation factors
• I Fibrinogen
• II Prothrombin
• VIII Antihaemophilic globulin (AHG),
antihaemophilic factor A
• IX Christmas factor, plasma
thromboplastin component (PTA),
antihaemophilic factor B
• XI Plasma thromboplastin antecedent
(PTA), antihaemophilic factor C
• Vitamin K is essential for synthesis of factors II, VII, IX and X.
7. What is basis for the Rh system? Write a note on hemolytic disease of the newborn
(erythroblastosis fetalis).
Answer: The red blood cell membrane antigen important here is the Rhesus (Rh) antigen, or Rhesus factor.
About 85% of people have this antigen; they are Rhesus positive (Rh+) and do not therefore make anti-
Rhesus antibodies. The remaining 15% have no Rhesus antigen (they are Rhesus negative, or Rh−). Rh−
individuals are capable of making anti-Rhesus antibodies, but are stimulated to do so only in certain
circumstances, e.g. in pregnancy, or as the result of an incompatible blood transfusion.
Erythroblastosis fetalis
In this disorder, the mother’s immune system makes antibodies to the baby’s red blood cells, causing
destruction of fetal erythrocytes. The antigen system involved is usually (but not always) the Rhesus (Rh)
antigen. A Rh− mother carries no Rh antigen on her red blood cells, but she has the capacity to produce
anti-Rh antibodies. If she conceives a child fathered by a Rh+ man, and the baby inherits the Rh antigen
from him, the baby may also be Rh+, i.e. different from the mother. During pregnancy, the placenta protects
the baby from the mother’s immune system, but at delivery a few fetal red blood cells may enter the
maternal circulation. Because they carry an antigen (the Rh antigen) foreign to the mother, her immune
system will be stimulated to produce neutralising antibodies to it. The red cells of second and subsequent
Rh+ babies are attacked by these maternal antibodies, which can cross the placenta and enter the fetal
circulation. In the most severe cases, the baby dies in the womb from profound anaemia. In less serious
circumstances, the baby is born with some degree of anaemia, which is corrected with blood transfusions.
8. Describe the constituents of plasma and their functions ?

Answer:
OTHER SOLUTES (1.5%) Inorganic salts. Positively charges ions(cations) include Na+,K+,Ca+,Mg2+;
ELECTROLYTES Negatively charged ions(anions) include Cl-,HPO42-,SO42-,HCO3-. Help maintain
osmotic pressure and plays essential roles in function of cells.
NUTRIENTS Products of digestion pass into blood for distribution to all body cells. Includes amino
acids(from proteins), glucose(from carbohydrates), fatty acids and glycerol(from
triglycerides), vitamins and minerals.
ELNAZ. Z 21
GASES Oxygen, Carbon dioxide and Nitrogen. More O2 is associated with hemoglobin inside
red blood cells; more CO2 is dissolved in plasma. N2 is present but has no known
functions in the body.
REGULATORY Enzymes, produces by body cells, catalyze chemical reactions. Hormones, produced
SUBSTANCES by endocrine glands, regulate metabolism, growth and development. Vitamins are
cofactors for enzymatic reactions.
WASTE PRODUCTS Most are breakdown products of protein metabolism and are carried by blood to organs
of excretion. Include urea, uric acid, creatine, creatinine, bilirubin and ammonia.
WATER (91.5%) Liquid portion of blood. Acts as solvent and suspending medium for components of
blood; absorbs, transports and releases heat.
PLASMA PROTEIN Exert colloid osmotic pressure, which helps maintain water balance between blood and
(7.0%) tissues and regulates blood volume.
ALBUMIN Smallest and most numerous blood plasma proteins; produces by liver. Transports
proteins for several steroid hormones and for fatty acids.
GLOBULINS Produces by liver and plasma cells, which develop from B lymphocytes. Antibodies
help attack viruses and bacteria. Alpha and beta globulins transport iron, lipids and fat
soluble vitamin.
SHORT ANSWERS (2M)
1. What is anemia.? How it is caused.

Answer: Anaemia is the inability of the blood to carry enough oxygen to meet body needs. Usually this is
because there are low levels of haemoglobin in the blood, but sometimes it is due to production of faulty
haemoglobin.
• Iron deficiency anemia
• Vitamin deficiency anemia
• Anemia of chronic disease
• Aplastic anemia
• Anemias associated with bone marrow disease
• Sickle cell anemia
• Other anemias
2. Write stages of formation of RBC

Answer:
Proerythroblast Erythroblast Reticulocyte Erythrocyte
3. Write the normal values and life span of the following:

(a)Hb; (b) WBC; (c) RBC; and (d) platelets
Answer: (a)Hb male: 13.5-17.5 gm/dl and Female: 12.5-15.5 (Life span-120 days)
(b) WBC (Life span- 13 to 20 days)
Granulocytes
• Neutrophils: 40 to 75%
• Eosinophils: 1 to 6%
• Basophils: < 1%
Agranulocytes
ELNAZ. Z 22
• Monocytes: 2 to 10%
• Lymphocytes: 20 to 50%
(c) RBC (Life span-120 days)
Male: 4.5–6.5 million/mm3
Female: 3.8–5.8 million/mm3
(d) Platelets (Life span 8-11 days)
150, 000 to 450,000/ml
4. Mention different types of anaemia.

Answer:
• Iron deficiency anemia
• Vitamin deficiency anemia
• Anemia of chronic disease
• Aplastic anemia
• Anemias associated with bone marrow disease
• Sickle cell anemia
• Other anemias
5. Thrombocytopenia purpura.
Answer: This condition, which usually affects children and young adults, may be triggered by a viral
infection such as measles. Antiplatelet antibodies are formed that coat platelets, leading to platelet
destruction and their removal from the circulation. A significant feature of this disease is the presence of
purpura, which are haemorrhages into the skin ranging in size from pinpoints to large blotches. The severity
of the disease varies from mild bleeding into the skin to severe haemorrhage.
6. What is polycythemia? Give its reasons.

Answer: This means an abnormally large number of erythrocytes in the blood. This increases blood
viscosity, slows blood flow and increases the risk of intravascular clotting, ischaemia and infarction.
• This occurs when the erythrocyte count is normal but the blood volume is reduced by fluid loss, e.g.
excessive serum exudate from extensive burns.
• Prolonged hypoxia stimulates erythropoiesis and the number of reticulocytes released into the
normal volume of blood is increased. This occurs naturally in people living at high altitudes where
the oxygen tension in the air is low and the partial pressure of oxygen in the alveoli of the lungs is
correspondingly low.
• Heart or lung disease or heavy smoking can also cause polycythaemia.
7. Write the functions of WBC

Answer:
Cells(WBCs) or
Leukocytes
Granular Leukocytes Phagocytosis. Destruction of bacteria with lysozymes, defensins and strong oxidants, such as
Neutrophiles superoxide anion, hydrogen peroxide, and hypochlorite anion.
Eosinophils Eliminates parasites, such as worms which are too big to be phagocytosed; phagocytes antigen-
antibody complexes & combat the effects of histamine in allergic reactions.
Basophils Liberate heparin, histamine and serotonin in allergic reactions that intensify the overall
inflammatory response.
Agranular Leukocytes Medium immune response, including antigen-antibody reactions. B cells develop into plasma
Lymphocytes(T cells, B cells, which secrete antibodies, T cells attack invading viruses, cancer cells, and transplanted
cells & natural killer tissue cells. Natural killer calls attach a wide variety of infectious microbes and certain
cells) spontaneously arising tumor cells.
ELNAZ. Z 23
Monocytes Acts on the hypothalamus, causing the rise in body temperature with microbial infections;
stimulates the production of some globulins by the liver; enhances the production of activated T-
lymphocytes; Phagocytosis.
8. Write functions of plasma proteins.

Answer:
PLASMA Exert colloid osmotic pressure, which helps maintain water balance between blood and tissues and
PROTEIN (7.0%) regulates blood volume.
ALBUMIN Smallest and most numerous blood plasma proteins; produces by liver. Transports proteins for
several steroid hormones and for fatty acids.
GLOBULINS Produces by liver and plasma cells, which develop from B lymphocytes. Antibodies help attack
viruses and bacteria. Alpha and beta globulins transport iron, lipids and fat soluble vitamin.
9. What is Rh factor?
Answer: The red blood cell membrane antigen important here is the Rhesus (Rh) antigen, or Rhesus factor.
About 85% of people have this antigen; they are Rhesus positive (Rh+) and do not therefore make anti-
Rhesus antibodies. The remaining 15% have no Rhesus antigen (they are Rhesus negative, or Rh−). Rh−
individuals are capable of making anti-Rhesus antibodies, but are stimulated to do so only in certain
circumstances, e.g. in pregnancy, or as the result of an incompatible blood transfusion.
10. What is the difference between plasma and serum?

Answer: Serum is that part of blood which is similar in composition with plasma but exclude clotting
factors of blood. Plasma is considered as the medium of blood in which RBCs, WBC and other components
of blood are suspended. The components of plasma and serum are similar as both contain hormones,
glucose, electrolytes, antibodies, antigens, nutrients and certain other particles except clotting factors which
are present only in plasma. [Plasma – clotting factors = Serum]
11. Compare erythrocytes, leukocytes, and thrombocytes with respect to size, number per mm3,
and life span.
Answer: Refer Question:3(2 mark)
12. What is hemophilia? Describe its signs and symptoms.

Answer: Hemophilia is an inherited deficiency of clotting in which bleeding may occur spontaneously or
after only minor trauma. Hemophilia is characterized by spontaneous or traumatic subcutaneous and
intramuscular hemorrhaging, nosebleeds, blood in the urine, and hemorrhages in joints that produce pain
and tissue damage.
13. Write any four factors hastening the clotting.

Answer:
• I Fibrinogen
• II Prothrombin
• VIII Antihaemophilic globulin (AHG), antihaemophilic factor A
• IX Christmas factor, plasma thromboplastin component (PTA), antihaemophilic factor B
• XI Plasma thromboplastin antecedent (PTA), antihaemophilic factor C
• Vitamin K is essential for synthesis of factors II, VII, IX and X.
ELNAZ. Z 24
CHAPTER 6.THE LYMPHATIC SYSTEM
SHORT ESSAYS (5M)
1. Describe the anatomy and functions of spleen.

Answer: The oval spleen is the largest single mass
of lymphatic tissue in the body, measuring about 12
cm (5 in.) in length. It is located in the left
hypochondriac region between the stomach and
diaphragm. The superior surface of the spleen is
smooth and convex and conforms to the concave
surface of the diaphragm. Neighboring organs make
indentations in the visceral surface of the spleen—the
gastric impression (stomach), the renal impression
(left kidney), and the colic impression (left colic
flexure of large intestine). Like lymph nodes, the
spleen has a hilum. Through it pass the splenic artery,
splenic vein, and efferent lymphatic vessels. Blood flowing into the spleen through the splenic artery enters
the central arteries of the white pulp. Within the white pulp, B cells and T cells carry out immune functions,
similar to lymph nodes, while spleen macrophages destroy blood-borne pathogens by phagocytosis. Within
the red pulp, the spleen performs three functions related to blood cells: (1) removal by macrophages of
ruptured, worn out, or defective blood cells and platelets; (2) storage of platelets, up to one-third of the
body’s supply; and (3) production of blood cells (hemopoiesis) during fetal life.
2. Write a note on lymph and its functions.

Answer: Lymph is a clear watery fluid, similar in composition to plasma, with the important exception of
plasma proteins, and identical in composition to interstitial fluid. Lymph transports the plasma proteins that
seep out of the capillary beds back to the bloodstream. It also carries away larger particles, e.g. bacteria and
cell debris from damaged tissues, which can then be filtered out and destroyed by the lymph nodes. Lymph
contains lymphocytes (defence cells), which circulate in the lymphatic system allowing them to patrol the
different regions of the body. In the lacteals of the small intestine, fats absorbed into the lymphatics give
the lymph (now called chyle), a milky appearance.
a. Lymph helps in transports oxygen, food materials, hormones, etc., to the body cells and brings
carbon dioxide and other metabolic wastes, from the body cells to blood and then finally pours the
same into the venous system.
b. Body cells are kept moist by the lymph.
c. Lymph nodes produce lymphocytes. Lymph takes lymphocytes and antibodies from the lymph
nodes to the blood.'
d. It destroys the invading microorganisms and foreign particles in the lymph nodes.
e. It absorbs and transports fat and fat soluble vitamins from the intestine. Lymph capillaries present
in the intestinal villi are called lacteals which are associated with absorption and transportation of
fat and fat soluble vitamins.
f. It brings plasma protein macromolecules synthesized in the liver cells and hormones produced in
the endocrine glands to the blood. These molecules cannot pass into the narrow blood capillaries
but can diffuse into the lymphatic capillaries.
g. Lymph maintains the volume of the blood, as soon as the volume of the blood reduces in the blood
vascular system, the lymph rushes from the lymphatic systems to the blood vascular system.
3. Identify the components and functions of lymphatic system.

Answer: • Lymph
• Lymph vessels
• Lymph nodes
• Lymph organs, e.g. spleen and thymus
• Diffuse lymphoid tissue, e.g. tonsils
ELNAZ. Z 25
• Bone marrow.
Functions of the Lymphatic System
The lymphatic system has three primary functions:
1. Drains excess interstitial fluid. Lymphatic vessels drain excess interstitial fluid from tissue spaces and
return it to the blood.
2. Transports dietary lipids. Lymphatic vessels transport lipids and lipid-soluble vitamins (A, D, E, and
K) absorbed by the gastrointestinal tract.
3. Carries out immune responses. Lymphatic tissue initiates highly specific responses directed against
particular microbes or abnormal cells.
4. Describe the structure of a lymph node. Write its functions.

Answer: Functions
• Filtering and phagocytosis
Lymph is filtered by the reticular and lymphatic tissue asit
passes through lymph nodes. Particulate matter may include
bacteria, dead and live phagocytes containing ingested
microbes, cells from malignant tumours, worn out and damaged
tissue cells and inhaled particles. Organic material is destroyed
in lymph nodes by macrophages and antibodies. Some inorganic
inhaled particles cannot be destroyed by phagocytosis. These
remain inside the macrophages, either causing no damage or
killing the cell. Material not filtered out and dealt with in one
lymph node passes on to successive nodes and by the time lymph
enters the blood it has usually been cleared of foreign matter and
cell debris. In some cases where phagocytosis of bacteria is
incomplete they may stimulate inflammation and enlargement
of the node (lymphadenopathy).
• Proliferation of lymphocytes
Activated T- and B-lymphocytes multiply in lymph nodes. Antibodies produced by sensitised B-
lymphocytes enter lymph and blood draining the node. Shows a scanning electron micrograph of lymph
node tissue, with reticular cells, white blood cells and macrophages.
5. Write a note on disorders of lymph and lymphatic system.

Answer: Disorders of the lymphatic system
Disorders of the lymphatic system involve one or more of the following:

• Obstruction
• Infection or inflammation
• Cancer
Obstruction leads to accumulation of lymphatic fluid in tissues (lymphedema) and is usually secondary to
surgery, radiation therapy, injury, or, in tropical countries, lymphatic filariasis. Rarely, the cause is a
congenital disorder (see Lymphedema : Primary lymphedemas).
Infection may cause reactive lymph node enlargement (lymphadenopathy) or the nodes themselves may
become infected (lymphadenitis) by organisms spread through the lymphatic system from the primary site
of infection.
Various cancers may metastasize to local or regional lymph nodes. Rarely, a primary cancer (eg,
lymphangiosarcoma, Non-Hodgkin’s lymphoma (NHL)) develops in the lymphatic system.
SHORT ANSWERS (2M)

1. What are lymph nodes?
Answer: Lymph nodes are oval or bean-shaped organs that lie, often in groups, along the length of lymph
vessels. The lymph drains through a number of nodes, usually 8–10, before returning to the venous
ELNAZ. Z 26
circulation. Activated T- and B-lymphocytes multiply in lymph nodes. Antibodies produced by sensitised
B-lymphocytes enter lymph and blood draining the node. Lymph is filtered by the reticular and lymphatic
tissue as it passes through lymph nodes.
2. Write about the functions of spleen.

Answer: The spleen performs three functions related to blood cells: (1) removal by macrophages of
ruptured, worn out, or defective blood cells and platelets; (2) storage of platelets, up to one-third of the
body’s supply; and (3) production of blood cells (hemopoiesis) during fetal life.
3. Write the composition of lymph.

Answer: Lymph is a clear watery fluid, similar in composition to plasma, with the important exception of
plasma proteins, and identical in composition to interstitial fluid. Lymph transports the plasma proteins that
seep out of the capillary beds back to the bloodstream. It also carries away larger particles, e.g. bacteria and
cell debris from damaged tissues, which can then be filtered out and destroyed by the lymph nodes. Lymph
contains lymphocytes (defence cells), which circulate in the lymphatic system allowing them to patrol the
different regions of the body. In the lacteals of the small intestine, fats absorbed into the lymphatics give
the lymph (now called chyle), a milky appearance.
4. Write the functions of lymph nodes

Answer: Functions
• Filtering and phagocytosis -Lymph is filtered by the reticular and lymphatic tissue asit passes
through lymph nodes. Particulate matter may include bacteria, dead and live phagocytes containing
ingested microbes, cells from malignant tumours, worn out and damaged tissue cells and inhaled
particles. Organic material is destroyed in lymph nodes by macrophages and antibodies.
• Proliferation of lymphocytes -Activated T- and B-lymphocytes multiply in lymph nodes.
Antibodies produced by sensitised B-lymphocytes enter lymph and blood draining the node. Shows
a scanning electron micrograph of lymph node tissue, with reticular cells, white blood cells and
macrophages.
5. What is lymphoedema and splenomegaly?

Answer: Lymphoedema - Swelling in tissues whose lymphatic drainage has been obstructed in some way.
Splenomegaly- This is enlargement of the spleen, and is usually secondary to other conditions, e.g.
infections, circulatory disorders, blood diseases, malignant neoplasms.
CHAPTER 7. CARDIOVASCULAR SYSTEM
LONG ESSAYS (10M)

1. Describe the internal anatomy of heart with a neat labelled diagram.
Answer:
Structure of the Heart Wall
The heart wall is made of 3 layers: epicardium, myocardium and endocardium.
ELNAZ. Z 27
• Epicardium. It is the outermost layer
of the heart wall and it is a thin layer of
serous membrane that helps to lubricate
and protect the outside of the heart.
• Myocardium. It is the muscular middle

layer of the heart wall that contains
the cardiac muscle tissue. Myocardium
makes up the majority of the thickness
and mass of the heart wall and is the part
of the heart responsible for pumping
blood. Below the myocardium is the thin
endocardium layer.
•Endocardium. It is the simple

squamous endothelium layer that lines
the inside of the heart. The endocardium
is very smooth and is responsible for keeping blood from sticking to the inside of the heart and forming
potentially deadly blood clots.
Chambers of the Heart
The heart contains 4 chambers: the right atrium, left atrium, right ventricle, and left ventricle. The atria
are smaller than the ventricles and have thinner, less muscular walls than the ventricles. The atria act as
receiving chambers for blood, so they are connected to the veins that carry blood to the heart. The ventricles
are the larger, stronger pumping chambers that send blood out of the heart. The ventricles are connected to
the arteries that carry blood away from the heart.
The chambers on the right side of the heart are smaller and have less myocardium in their heart wall when
compared to the left side of the heart. This difference in size between the sides of the heart is related to
their functions and the size of the 2 circulatory loops. The right side of the heart maintains pulmonary
circulation to the nearby lungs while the left side of the heart pumps blood all the way to the extremities of
the body in the systemic circulatory loop.
Valves of the Heart

The heart functions by pumping blood both to the lungs and to the systems of the body. To prevent blood
from flowing backwards or “regurgitating” back into the heart, a system of one-way valves is present in the
heart. The heart valves can be broken down into two types: atrioventricular and semilunar valves.
• Atrioventricular valves. They are located in the middle of the heart between the atria and ventricles and
only allow blood to flow from the atria into the ventricles. The AV valve on the right side of the heart is
called the tricuspid valve because it is made of three cusps (flaps) that separate to allow blood to pass
through and connect to block regurgitation of blood. The AV valve on the left side of the heart is called
the mitral valve or the bicuspid valve because it has two cusps. The AV valves are attached on the
ventricular side to tough strings called chordae tendineae. The chordae tendineae pull on the AV valves
to keep them from folding backwards and allowing blood to regurgitate past them. During the contraction
of the ventricles, the AV valves look like domed parachutes with the chordae tendineae acting as the
ropes holding the parachutes taut.
• Semilunar valves. They are located between the ventricles and the arteries that carry blood away from the
heart. The semilunar valve on the right side of the heart is the pulmonary valve, so named because it
prevents the backflow of blood from the pulmonary trunk into the right ventricle. The semilunar valve on
the left side of the heart is the aortic valve, named for the fact that it prevents the aorta from regurgitating
blood back into the left ventricle. The semilunar valves are smaller than the AV valves and do not have
chordae tendineae to hold them in place.
Conduction System of the Heart

The conduction system starts with the pacemaker of the heart—a small bundle of cells known as the
sinoatrial (SA) node. The SA node is located in the wall of the right atrium inferior to the superior vena
cava. The SA node is responsible for setting the pace of the heart as a whole and directly signals the atria
ELNAZ. Z 28
to contract. The signal from the SA node is picked up by another mass of conductive tissue known as the
atrioventricular (AV) node.
The AV node is located in the right atrium in the inferior portion of the interatrial septum. The AV node
picks up the signal sent by the SA node and transmits it through the atrioventricular (AV) bundle. The
AV bundle is a strand of conductive tissue that runs through the interatrial septum and into the
interventricular septum. The AV bundle splits into left and right branches in the interventricular septum
and continues running through the septum until they reach the apex of the heart. Branching off from the
left and right bundle branches are many Purkinje fibers that carry the signal to the walls of the ventricles,
stimulating the cardiac muscle cells to contract in a coordinated manner to efficiently pump blood out of
the heart.
2. Define blood pressure and discuss various factors regulating the blood pressure in human being.
Answer: Blood pressure is the force or pressure that the blood exerts on the walls of blood vessels.
Systolic and diastolic pressures - When the left ventricle contracts and pushes blood into the aorta, the
pressure produced within the arterial system is called the systolic blood pressure. In adults, it is about 120
mmHg. In complete cardiac diastole when the heart is resting following the ejection of blood, the pressure
within the arteries is much lower and is called diastolic blood pressure. In an adult, this is about 80 mmHg.
The difference between systolic and diastolic blood pressures is the pulse pressure.
factors regulating the blood pressure
Blood pressure is determined by cardiac output and peripheral resistance. Change in either of these
parameters tends to alter systemic blood pressure, although the body’s compensatory mechanisms usually
adjust for any significant change.
• Cardiac output
Cardiac output is determined by the stroke volume and the heart rate. Factors that affect the heart rate and
stroke volume are Autonomic nervous system, Circulating chemicals, Position, Exercise, Emotional states,
Gender, Age, Temperature and Baroreceptor reflex and they may increase or decrease cardiac output and,
in turn, blood pressure. An increase in cardiac output raises both systolic and diastolic pressures. An
increase in stroke volume increases systolic pressure more than diastolic pressure.
• Peripheral or arteriolar resistance
Arterioles, the smallest arteries, have a tunica media composed almost entirely of smooth muscle, which
responds to nerve and chemical stimulation. Constriction and dilation of the arterioles are the main
determinants of peripheral resistance. Vasoconstriction causes blood pressure to rise and vasodilation
causes it to fall. When elastic tissue in the tunica media is replaced by inelastic fibrous tissue as part of the
ageing process, blood pressure rises.
• Autoregulation
Systemic blood pressure continually rises and falls, according to levels of activity, body position, etc.
However, the body organs are capable of adjusting blood flow and blood pressure in their own local vessels
independently of systemic blood pressure. This property is called autoregulation, and protects the tissues
against swings in systemic pressures. It is especially important in the kidneys, which can be damaged by
increased pressure in their delicate glomerular capillary beds, and in the brain, which is very sensitive to
even slight increases in levels of cellular waste.
3. What is cardiac cycle? Describe various events of cardiac cycle.

Answer: The cardiac cycle - At rest, the healthy adult heart is likely to beat at a rate of 60–80 beats per
minute (b.p.m.). During each heartbeat, or cardiac cycle, the heart contracts (systole) and then relaxes
(diastole).
ELNAZ. Z 29
Stages of the cardiac cycle
Taking 74 b.p.m. as an example,
each cycle lasts about 0.8 of a
second and consists of:
• Atrial systole – contraction of the
atria
• Ventricular systole – contraction
of the ventricles
• Complete cardiac diastole –
relaxation of the atria and
ventricles.
It does not matter at which stage of
the cardiac cycle a description
starts. For convenience, the period
when the atria are filling has been
chosen.
The superior vena cava and the
inferior vena cava transport
deoxygenated blood into the right
atrium at the same time as the four pulmonary veins bring oxygenated blood into the left atrium. The
atrioventricular valves are open and blood flows passively through to the ventricles. The SA node triggers
a wave of contraction that spreads over the myocardium of both atria, emptying the atria and completing
ventricular filling (atrial systole 0.1 s). When the electrical impulse reaches the AV node it is slowed down,
delaying atrioventricular transmission. This delay means that the mechanical result of atrial stimulation,
atrial contraction, lags behind the electrical activity by a fraction of a second. This allows the atria to finish
emptying into the ventricles before the ventricles begin to contract. After this brief delay, the AV node
triggers its own electrical impulse, which quickly spreads to the ventricular muscle via the AV bundle, the
bundle branches and Purkinje fibres. This results in a wave of contraction which sweeps upwards from the
apex of the heart and across the walls of both ventricles pumping the blood into the pulmonary artery and
the aorta (ventricular systole 0.3 s). The high pressure generated during ventricular contraction forces the
atrioventricular valves to close, preventing backflow of blood into the atria.
After contraction of the ventricles there is complete cardiac diastole, a period of 0.4 seconds, when atria
and ventricles are relaxed. During this time, the myocardium recovers ready for the next heartbeat, and the
atria refill ready for the next cycle.
The valves of the heart and of the great vessels open and close according to the pressure within the chambers
of the heart. The AV valves are open while the ventricular muscle is relaxed during atrial filling and systole.
When the ventricles contract there is a rapid increase in the pressure in these chambers, and when it rises
above atrial pressure the atrioventricular valves close. When the ventricular pressure rises above that in the
pulmonary artery and in the aorta, the pulmonary and aortic valves open and blood flows into these vessels.
When the ventricles relax and the pressure within them falls, the reverse process occurs. First the pulmonary
and aortic valves close, then the atrioventricular valves open and the cycle begins again. This sequence of
opening and closing valves ensures that the blood flows in only one direction.
SHORT ESSAYS (5M)

1. Explain the normal ECG with labelled diagram.
ELNAZ. Z 30
Answer: The body tissues and fluids conduct
electricity well, so the electrical activity in the
heart can be recorded on the skin surface using
electrodes positioned on the limbs and/or the
chest. This recording, called an electrocardiogram
(ECG) shows the spread of the electrical signal
generated by the SA node as it travels through the
atria, the AV node and the ventricles. The normal
ECG tracing shows five waves which, by
convention, have been named P, Q, R, S and T.
The P wave arises when the impulse from the SA
node sweeps over the atria (atrial depolarisation).
The QRS complex represents the very rapid spread

of the impulse from the AV node through the AV
bundle and the Purkinje fibres and the electrical
activity of the ventricular muscle (ventricular depolarisation). Note the delay between the completion of
the P wave and the onset of the QRS complex. This represents the conduction of the impulse through the
AV node, which is much slower than conduction elsewhere in the heart, and allows atrial contraction to
finish completely before ventricular contraction starts. The T wave represents the relaxation of the
ventricular muscle (ventricular repolarisation). Atrial repolarisation occurs during ventricular contraction,
and so is not seen because of the larger QRS complex.
The ECG described above originates from the SA node and is called sinus rhythm. The rate of sinus rhythm
is 60–100 b.p.m. A faster heart rate is called tachycardia and a slower heart rate, bradycardia. By
examining the pattern of waves and the time interval between cycles and parts of cycles, information about
the state of the myocardium and the cardiac conduction system is obtained.
2. Explain systemic and pulmonary circulation.

Answer: Systemic circulation is the movement of blood from the heart through the body to provide
oxygen and nutrients to the tissues of the body while bringing deoxygenated blood back to the heart.
Oxygenated blood enters the left atrium from the pulmonary veins. The blood is then pumped through
the mitral valve into the left ventricle. From the left ventricle, blood is pumped through the aortic valve and
into the aorta, the body's largest artery. The aorta arches and branches into major arteries to the upper body
before passing through the diaphragm, where it branches further into the illiac, renal, and suprarenal arteries
which supply the lower parts of the body.
The arteries branch into smaller arteries, arterioles, and finally capillaries. Gas and nutrient exchange with
the tissues occurs within the capillaries that run through the tissues. Metabolic waste and carbon dioxide
diffuse out of the cell into the blood, while oxygen and glucose in the blood diffuses out of the blood and
into the cell. Systemic circulation keeps the metabolism of every organ and every tissue in the body alive,
with the exception of the parenchyma of the lungs, which are supplied by pulmonary circulation.
The deoxygenated blood continues through the capillaries which merge into venules, then veins, and finally
the venae cavae, which drain into the right atrium of the heart. From the right atrium, the blood will travel
through the pulmonary circulation to be oxygenated before returning gain to the systemic circulation,
completing the cycle of circulation through the body.
Pulmonary circulation is the movement of blood from the heart to the lungs for oxygenation, then back
to the heart again. Deoxygenated blood from the body leaves the systemic circulation when it enters the
right atrium through the superior and inferior venae cavae. The blood is then pumped through the tricuspid
valve into the right ventricle. From the right ventricle, blood is pumped through the pulmonary valve and
into the pulmonary artery. The pulmonary artery splits into the right and left pulmonary arteries and travel
to each lung.
At the lungs, the blood travels through capillary beds on the alveoli where gas exchange occurs, removing
carbon dioxide and adding oxygen to the blood. Gas exchange occurs due to gas partial
pressure gradients across the the alveoli of the lungs and the capillaries interwoven in the alveoli. The
oxygenated blood then leaves the lungs through pulmonary veins, which returns it to the left atrium,
completing the pulmonary circuit. As the pulmonary circuit ends, the systemic circuit begins.
ELNAZ. Z 31
3. Explain coronary and portal blood circulation.
Answer: In the portal circulation, venous blood from the capillary beds of the abdominal part of the
digestive system, the spleen and pancreas travels first to the liver. In the liver, it passes through a second
capillary bed, the hepatic sinusoids, before entering the general circulation via the inferior vena cava. In
this way, blood with a high concentration of nutrients, absorbed from the stomach and intestines, goes to
the liver first. This supplies the liver with a rich source of nutrients for its extensive metabolic activities
and ensures that the composition of blood leaving the alimentary tract can be appropriately regulated. It
also ensures that unwanted and/or potentially toxic materials such as drugs are eliminated before the blood
is returned into general circulation. After blood has passed through the hepatic portal circulation, it is then
returned directly to the inferior vena cava through the hepatic veins.
Arterial supply- The heart is supplied with arterial blood by the right and left coronary arteries, which
branch from the aorta immediately distal to the aortic valve. The coronary arteries receive about 5% of the
blood pumped from the heart, although the heart comprises a small proportion of body weight. This large
blood supply, of which a large proportion goes to the left ventricle, highlights the importance of the heart
to body function. Venous drainage. Most of the venous blood is collected into a number of cardiac veins
that join to form the coronary sinus, which opens into the right atrium. The remainder passes directly into
the heart chambers through little venous channels.
4. Write short note on heart valves and heart sounds.

Answer: Valves of the Heart
The heart functions by pumping blood both to the lungs and to the systems of the body. To prevent blood
from flowing backwards or “regurgitating” back into the heart, a system of one-way valves is present in the
heart. The heart valves can be broken down into two types: atrioventricular and semilunar valves.
• Atrioventricular valves. They are located in the middle of the heart between the atria and ventricles
and only allow blood to flow from the atria into the ventricles. The AV valve on the right side of
the heart is called the tricuspid valve because it is made of three cusps (flaps) that separate to allow
blood to pass through and connect to block regurgitation of blood. The AV valve on the left side of
the heart is called the mitral valve or the bicuspid valve because it has two cusps. The AV valves
are attached on the ventricular side to tough strings called chordae tendineae. The chordae
tendineae pull on the AV valves to keep them from folding backwards and allowing blood to
regurgitate past them. During the contraction of the ventricles, the AV valves look like domed
parachutes with the chordae tendineae acting as the ropes holding the parachutes taut.
• Semilunar valves. They are located between the ventricles and the arteries that carry blood away
from the heart. The semilunar valve on the right side of the heart is the pulmonary valve, so named
because it prevents the backflow of blood from the pulmonary trunk into the right ventricle. The
semilunar valve on the left side of the heart is the aortic valve, named for the fact that it prevents
the aorta from regurgitating blood back into the left ventricle. The semilunar valves are smaller
than the AV valves and do not have chordae tendineae to hold them in place.
Heart Sound
There are four heart sounds, each corresponding to a particular event in the cardiac cycle. The first two are
most easily distinguished, and sound through the stethoscope like ‘lub dup’. The first sound, ‘lub’, is fairly
loud and is due to the closure of the atrioventricular valves. This corresponds with the start of ventricular
systole. The second sound, ‘dup’, is softer and is due to the closure of the aortic and pulmonary valves.
This corresponds with ventricular diastole.
5. Explain the gross anatomy of heart

Answer: Refer Question 1 (10 mark)
6. Discuss the factors regulating blood pressure.

Answer: Refer Question 2 (10 mark)
SHORT ANSWERS(2M)
1. Explain heart sounds
ELNAZ. Z 32
Answer: There are four heart sounds, each corresponding to a particular event in the cardiac cycle. The
first two are most easily distinguished, and sound through the stethoscope like ‘lub dup’. The first sound,
‘lub’, is fairly loud and is due to the closure of the atrioventricular valves. This corresponds with the start
of ventricular systole. The second sound, ‘dup’, is softer and is due to the closure of the aortic and
pulmonary valves. This corresponds with ventricular diastole.
2. Define the term -angina pectoris and myocardial infarction.

Answer: Angina pectoris, commonly known as angina, is the sensation of chest pain, pressure, or
squeezing, often due to not enough blood flow to the heart muscle as a result of obstruction or spasm of
the coronary arteries. Myocardial infarction (MI) (ie, heart attack) is the irreversible death (necrosis) of
heart muscle secondary to prolonged lack of oxygen supply (ischemia).
3. Define cardiac arrhythmia.

Answer: Cardiac arrhythmia, also known as cardiac dysrhythmia or irregular heartbeat, is a group
of conditions in which the heartbeat is irregular, too fast, or too slow. A heart rate that is too fast – above
100 beats per minute in adults – is called tachycardia and a heart rate that is too slow – below 60 beats per
minute – is called bradycardia.
4. Define Atherosclerosis and Congestive cardiac failure.

Answer: Atherosclerosis is hardening and narrowing of the arteries silently and slowly blocks arteries,
putting blood flow at risk which in turn leads to heart attack, stroke etc. Heart failure (HF), often referred to
as congestive cardiac failure (CHF or CCF), occurs when the heart is unable to pump sufficiently to maintain blood
flow to meet the body's needs.
5. What is cardiac output? How it is calculated.

Answer: The cardiac output is the amount of blood ejected from each ventricle every minute. The amount
expelled by each contraction of each ventricle is the stroke volume. Cardiac output is expressed in litres per
minute (L/min). In a healthy adult at rest, the stroke volume is approximately 70 mL and if the heart rate is
72 per minute, the cardiac output is 5 L/minute.
Cardiac output = Stroke volume × Heart rate.
6. Draw ECG and label deflection waves.

Answer: Refer question 1 (5M)
7. Define hypertension and hypotension.

Answer: Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long term medical
condition in which the blood pressure in the arteries is persistently elevated. Hypotension is low blood
pressure, especially in the arteries of the systemic circulation.[1] Blood pressure is the force of blood
pushing against the walls of the arteries as the heart pumps out blood. A systolic blood pressure of less than
90 millimeters of mercury (mm Hg) or diastolic of less than 60 mm Hg is generally considered to be
hypotension.
8. Mention the factors affecting blood pressure.

9. Mention the events of cardiac cycle.

10 Mention the layers and valves of the heart.

ELNAZ. Z 33
CHAPTER 8 RESPIRATORY SYSTEM.
LONG ESSAYS (10M)

1. What is external respiration? Explain the regulation of respiration.
Answer: External respiration is exchange of gases by
diffusion between the alveoli and the blood in the alveolar
capillaries, across the respiratory membrane. Each alveolar
wall is one cell thick and is surrounded by a network of tiny
capillaries (the walls of which are also only one cell thick). The
total area of respiratory membrane for gas exchange in the
lungs is about equivalent to the area of a tennis court. Venous
blood arriving at the lungs in the pulmonary artery has travelled
from all the tissues of the body, and contains high levels of CO2
and low levels of O2. Carbon dioxide diffuses from venous
blood down its concentration gradient into the alveoli until
equilibrium with alveolar air is reached. By the same process,
oxygen diffuses from the alveoli into the blood. The relatively
slow flow of blood through the capillaries increases the time available for gas exchange to occur. When
blood leaves the alveolar capillaries, the oxygen and carbon dioxide concentrations are in equilibrium with
those of alveolar air.
Regulation of respiration
Effective control of respiration enables the body to regulate blood gas levels over a wide range of
physiological, environmental and pathological conditions, and is normally involuntary. Voluntary control
is exerted during activities such as speaking and singing but is overridden if blood CO2 rises (hypercapnia).
The respiratory centre
This is formed by groups of nerves in the medulla, the respiratory rhythmicity centre, which control the
respiratory pattern, i.e. the rate and depth of breathing. Regular discharge of inspiratory neurones within
this centre set the rate and depth of breathing. Activity of the respiratory rhythmicity centre is adjusted by
nerves in the pons (the pneumotaxic centre and the apneustic centre), in response to input from other parts
of the brain. Motor impulses leaving the respiratory centre pass in the phrenic and intercostal nerves to the
diaphragm and intercostal muscles respectively to stimulate respiration.
Chemoreceptors
These are receptors that respond to changes in the partial pressures of oxygen and carbon dioxide in the
blood and cerebrospinal fluid. They are located centrally and peripherally. Central chemoreceptors. These
are located on the surface of the medulla oblongata and are bathed in cerebrospinal fluid. When arterial
PCO2 rises (hypercapnia), even slightly, the central chemoreceptors respond by stimulating the respiratory
centre, increasing ventilation of the lungs and reducing arterial PCO2. The sensitivity of the central
chemoreceptors to raised arterial PCO2 is the most important factor in controlling normal blood gas levels.
A small reduction in PO2 (hypoxaemia) has the same, but less pronounced effect, but a substantial
reduction depresses breathing.
Peripheral chemoreceptors. These are situated in the arch of the aorta and in the carotid bodies. They
respond to changes in blood CO2 and O2 levels, but are much more sensitive to carbon dioxide than oxygen.
Even a slight rise in CO2 levels activates these receptors, triggering nerve impulses to the respiratory centre
via the glossopharyngeal and vagus nerves. This stimulates an immediate rise in the rate and depth of
respiration. An increase in blood acidity (decreased pH or raised [H+]) also stimulates the peripheral
chemoreceptors, resulting in increased ventilation, increased CO2 excretion and increased blood pH. These
chemoreceptors also help to regulate blood pressure.
2. Discuss gross anatomy of respiratory system with suitable diagram.
ELNAZ. Z 34
Answer: The organs of the respiratory system
are:
Nose-The nasal cavity is the main route of air
entry, and consists of a large irregular cavity
divided into two equal passages by a septum.
The posterior bony part of the septum is formed
by the perpendicular plate of the ethmoid bone
and the vomer. Anteriorly, it consists of
hyaline cartilage.
Pharynx- The walls of the pharynx contain
several types of tissue.
Mucous membrane lining -The mucosa varies
slightly in the different regions. In the
nasopharynx it is continuous with the lining of
the nose and consists of ciliated columnar epithelium; in the oropharynx and laryngopharynx it is formed
by tougher stratified squamous epithelium, which is continuous with the lining of the mouth and
oesophagus. This lining protects underlying tissues from the abrasive action of foodstuffs passing through
during swallowing.
The nasopharynx- The nasal part of the pharynx lies behind the noseabove the level of the soft palate. The
oropharynx- The oral part of the pharynx lies behind the mouth, extending from below the level of the soft
palate to the level of the upper part of the body of the 3rd cervical vertebra. The laryngopharynx- The
laryngeal part of the pharynx extends from the oropharynx above and continues as the oesophagus below,
with the larynx lying anteriorly.
Larynx- The larynx or ‘voice box’ links the laryngopharynx and the trachea. Cartilages The larynx is
composed of several irregularly shaped cartilages attached to each other by ligaments and membranes. The
main cartilages are:
• 1 thyroid cartilage
• 1 cricoid cartilage hyaline cartilage
• 2 arytenoid cartilages
• 1 epiglottis - elastic fibrocartilage
Trachea- The tracheal wall is composed of three layers of tissue, and is held open by between 16 and 20
incomplete (C-shaped) rings of hyaline cartilage lying one above the other. The rings are incomplete
posteriorly where the trachea lies against the oesophagus. The cartilages are embedded in a sleeve of smooth
muscle and connective tissue, which also forms the posterior wall where the rings are incomplete.
Lungs [Two bronchi (one bronchus to each lung), Two lungs and their coverings, the pleura and
Bronchioles and smaller air passages] - The lungs are pyramid-shaped, paired organs that are connected
to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the
diaphragm. The diaphragm is the flat, dome-shaped muscle located at the base of the lungs and thoracic
cavity. The lungs are enclosed by the pleurae, which are attached to the mediastinum. The right lung is
shorter and wider than the left lung, and the left lung occupies a smaller volume than the right.
The cardiac notch is an indentation on the surface of the left lung, and it allows space for the heart. The
apex of the lung is the superior region, whereas the base is the opposite region near the diaphragm. The
costal surface of the lung borders the ribs. The mediastinal surface faces the midline. Each lung is
composed of smaller units called lobes. Fissures separate these lobes from each other. The right lung
consists of three lobes: the superior, middle, and inferior lobes. The left lung consists of two lobes: the
superior and inferior lobes. A bronchopulmonary segment is a division of a lobe, and each lobe hous es
multiple bronchopulmonary segments. Each segment receives air from its own tertiary bronchus and is
supplied with blood by its own artery. Some diseases of the lungs typically affect one or more
bronchopulmonary segments, and in some cases, the diseased segments can be surgically removed with
little influence on neighboring segments. A pulmonary lobule is a subdivision formed as the bronchi
branch into bronchioles. Each lobule receives its own large bronchiole that has multiple branches. An
interlobular septum is a wall, composed of connective tissue, which separates lobules from one another.
Muscles of breathing– the intercostal muscles and the diaphragm
Intercostal muscles- There are 11 pairs of intercostal muscles occupying the spaces between the 12 pairs
of ribs. They are arranged in two layers, the external and internal intercostal muscles. The external
intercostal muscles These extend downwards and forwards from the lower border of the rib above to the
ELNAZ. Z 35
upper border of the rib below. They are involved in inspiration. The internal intercostal muscles These
extend downwards and backwards from the lower border of the rib above to the upper border of the rib
below, crossing the external intercostal muscle fibres at right angles. The internal intercostals are used when
expiration becomes active, as in exercise.
Diaphragm
The diaphragm is a dome-shaped muscular structure separating the thoracic and abdominal cavities. It
forms the floor of the thoracic cavity and the roof of the abdominal cavity and consists of a central tendon
from which muscle fibres radiate to be attached to the lower ribs and sternum and to the vertebral column
by two crura. When the diaphragm is relaxed, the central tendon is at the level of the 8th thoracic vertebra.
When it contracts, its muscle fibres shorten and the central tendon is pulled downwards to the level of the
9th thoracic vertebra, lengthening the thoracic cavity. This decreases pressure in the thoracic cavity and
increases it in the abdominal and pelvic cavities. The diaphragm is supplied by the phrenic nerves.
3. Give an account of transport of oxygen and carbon dioxide in the blood.

Answer: Venous blood arriving at the lungs in the pulmonary artery has travelled from all the tissues of
the body, and contains high levels of CO2 and low levels of O2. Carbon dioxide diffuses from venous blood
down its concentration gradient into the alveoli until equilibrium with alveolar air is reached. By the same
process, oxygen diffuses from the alveoli into the blood. The relatively slow flow of blood through the
capillaries increases the time available for gas exchange to occur. When blood leaves the alveolar
capillaries, the oxygen and carbon dioxide concentrations are in equilibrium with those of alveolar air.
Blood arriving at the tissues has been cleansed of its CO2 and saturated with O2 during its passage through
the lungs, and therefore has a higher PO2 and a lower PCO2 than the tissues. This creates concentration
gradients between capillary blood and the tissues, and gas exchange therefore occurs. O2 diffuses from the
bloodstream through the capillary wall into the tissues. CO2 diffuses from the cells into the extracellular
fluid, then into the bloodstream towards the venous end of the capillary.
Transport of gases in the bloodstream - Oxygen and carbon dioxide are carried in the blood in different
ways.
Oxygen is carried in the blood in:
• chemical combination with haemoglobin as oxyhaemoglobin (98.5%)
• solution in plasma water (1.5%).
Oxyhaemoglobin is unstable, and under certain conditions readily dissociates releasing oxygen. Factors
that increase dissociation include low O2 levels, low pH and raised temperature. In active tissues there is
increased production of carbon dioxide and heat, which leads to increased release of oxygen. In this way
oxygen is available to tissues in greatest need. Whereas oxyhaemoglobin is bright red, deoxygenated blood
is bluish-purple in colour.
Carbon dioxide is one of the waste products of metabolism. It is excreted by the lungs and is transported
by three mechanisms:
• as bicarbonate ions (HCO3 −) in the plasma (70%)
• some is carried in erythrocytes, loosely combined with haemoglobin as carbaminohaemoglobin (23%)
• some is dissolved in the plasma (7%).
4. Explain the mechanism of respiration.

Answer: The average respiratory rate is 12–15 breaths per minute. Each breath consists of three phases:
inspiration, expiration and pause. The visceral pleura is adherent to the lungs and the parietal pleura to
the inner wall of the thorax and to the diaphragm. Between them is a thin film of pleural fluid. Breathing
depends upon changes in pressure and volume in the thoracic cavity. It follows the underlying physical
principle that increasing the volume of a container decreases the pressure inside it, and that decreasing the
volume of a container increases the pressure inside it. Since air flows from an area of high pressure to an
area of low pressure, changing the pressure inside the lungs determines the direction of airflow.
Inspiration
Simultaneous contraction of the external intercostal muscles and the diaphragm expands the thorax. As the
parietal pleura is firmly adhered to the diaphragm and the inside of the ribcage, it is pulled outward along
with them. This pulls the visceral pleura outwards too, since the two pleura are held together by the thin
film of pleural fluid. Because the visceral pleura is firmly adherent to the lung, the lung tissue is, therefore,
also pulled up and out with the ribs, and downwards with the diaphragm. This expands the lungs, and the
ELNAZ. Z 36
pressure within the alveoli and in the air passages falls, drawing air into the lungs in an attempt to equalise
atmospheric and alveolar air pressures.
The process of inspiration is active, as it needs energy for muscle contraction. The negative pressure created
in the thoracic cavity aids venous return to the heart and is known as the respiratory pump. At rest,
inspiration lasts about 2 seconds.
Expiration
Relaxation of the external intercostal muscles and the diaphragm results in downward and inward
movement of the ribcage and elastic recoil of the lungs. As this occurs, pressure inside the lungs rises and
expels air from the respiratory tract. At the end of expiration, the lungs still contain some air, and are
prevented from complete collapse by the intact pleura. This process is passive as it does not require the
expenditure of energy. At rest, expiration lasts about 3 seconds, and after expiration there is a pause before
the next cycle begins.
SHORT ESSAYS (5M)

1. Write a short note on artificial respiration.
Answer: Artificial ventilation, also called artificial respiration is any means of assisting or
stimulating respiration, a metabolic process referring to the overall exchange of gases in the body by
pulmonary ventilation, external respiration, and internal respiration. It may take the form of manually
providing air for a person who is not breathing or is not making sufficient respiratory effort on their own, or
it may be mechanical ventilation involving the use of a mechanical ventilator to move air in and out of the
lungs when an individual is unable to breathe on their own, for example during surgery with general
anesthesia or when an individual is in a coma.
Manual methods- Pulmonary ventilation is achieved through manual insufflation of the lungs either by
the rescuer blowing into the patient's lungs (mouth-to-mouth resuscitation), or by using a mechanical device
to do so. Mouth-to-mouth resuscitation is also part of cardiopulmonary resuscitation (CPR) making it an
essential skill for first aid.
Mechanical ventilation- Mechanical ventilation is a method to mechanically assist or replace
spontaneous breathing. Mechanical ventilation is termed "invasive" if it involves any instrument
penetrating through the mouth or the skin.
2. Explain mechanism of breathing.

Answer: Refer Question 4 (10M)
3. Internal and external respiration.

Answer: Refer Question 1 & 3 (10M)
4. Describe the location and anatomy of lungs

Answer: The lungs lie either side of the mediastinum, within the thoracic cavity. Each lung is surrounded
by a pleural cavity, which is formed by the visceral and parietal pleura. They are suspended from the
mediastinum by the lung root – a collection of structures entering and leaving the lungs. The medial
surfaces of both lungs lie in close
proximity to several mediastinal
structures:
Bronchial Tree
ELNAZ. Z 37
The bronchial tree is a series of passages that supplies air to the
alveoli of the lungs. It begins with the trachea, which divides into
a left and right bronchus.
Each bronchus enters the root of the lung, passing through the
hilum. Inside the lung, they divide to form lobar bronchi – one
supplying each lobe.
Each lobar bronchus then further divides into several
tertiary segmental bronchi. Each segmental bronchi provides air
to a bronchopulmonary segment – these are the functional units of
the lungs.
The segmental bronchi give rise to many conducting bronchioles,
which eventually lead into terminal bronchioles. Each terminal
bronchiole gives off respiratory bronchioles, which feature thin
walled out pocketing’s that extend from their lumens. These are
the alveoli – the site of gaseous exchange.
5. Explain the lung volumes and capacities.

Answer: Tidal volume (TV). This is the amount of air passing
into and out of the lungs during each cycle of breathing (about
500 mL at rest).
Inspiratory reserve volume (IRV). This is the extra volume of
air that can be inhaled into the lungs during maximal inspiration,
i.e. over and above normal TV.
Inspiratory capacity (IC). This is the amount of air that can be
inspired with maximum effort. It consists of the tidal volume
(500 ml) plus the inspiratory reserve volume.
Functional residual capacity (FRC). This is the amount of air remaining in the air passages and alveoli
at the end of quiet expiration. The functional residual volume also prevents collapse of the alveoli on
expiration.
Expiratory reserve volume (ERV). This is the largest volume of air which can be expelled from the lungs
during maximal expiration.
Residual volume (RV). This cannot be directly measured but is the volume of air remaining in the lungs
after forced expiration.
Vital capacity (VC). This is the maximum volume of air which can be moved into and out of the lungs:
VC = Tidal volume + IRV + ERV
Total lung capacity (TLC). This is the maximum amount of air the lungs can hold. In an adult of average
build, it is normally around 6 litres. Total lung capacity represents the sum of the vital capacity and the
residual volume.
SHORT ANSWERS (2M)

1. Define vital capacity. Write its normal value.
Answer: Vital capacity (VC). This is the maximum volume of air which can be moved into and out of the
lungs: VC = Tidal volume + IRV + ERV (normal value is 4.8L)
2. Define hypoxia and asphyxia.

Answer: Hypoxia is a condition in which the body or a region of the body is deprived of
adequate oxygen supply at the tissue level. Asphyxia is the condition where the body either doesn't get
enough oxygen to continue normal function or has too much carbon dioxide to function properly.
3. Define oxygen therapy and resuscitation.

Answer: Oxygen therapy, also known as supplemental oxygen, is the use of oxygen as a medical
treatment. This can include for low blood oxygen, carbon monoxide toxicity, cluster headaches, and to
maintain enough oxygen while inhaled anesthetics are given. Resuscitation is the process of
correcting physiological disorders in an acutely unwell patient. It is an important part of intensive care
ELNAZ. Z 38
medicine, trauma surgery and emergency medicine. Well known examples are cardiopulmonary
resuscitation and mouth-to-mouth resuscitation.
4. Define dysbarism and tidal volume.

Answer: Dysbarism refers to medical conditions resulting from changes in ambient pressure. Various
activities are associated with pressure changes. underwater diving is the most frequently cited example, but
pressure changes also affect people who work in other pressurized environments (for
example, caisson workers), and people who move between different altitudes. Tidal volume (TV). This is
the amount of air passing into and out of the lungs during each cycle of breathing (about 500 mL at rest).
5. Name the muscles of respiration.

Answer: The muscles of respiration are those muscles that contribute to inhalation and exhalation, by
aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent,
the intercostal muscles drive respiration during quiet breathing. There are three layers of intercostal
muscles. The external intercostal muscles are most significant in respiration. These have fibres that are
angled obliquely downward and forward from rib to rib. The contraction of these fibres raises each rib
toward the rib above, with the overall effect of raising the rib cage, assisting in inhalation.
6. Write the role of chemo receptors in respiration.

Answer: These are receptors that respond to changes in the partial pressures of oxygen and carbon dioxide
in the blood and cerebrospinal fluid. They are located centrally and peripherally. Central chemoreceptors.
These are located on the surface of the medulla oblongata and are bathed in cerebrospinal fluid. When
arterial PCO2 rises (hypercapnia), even slightly, the central chemoreceptors respond by stimulating the
respiratory centre, increasing ventilation of the lungs and
reducing arterial PCO2. Peripheral chemoreceptors.
These are situated in the arch of the aorta and in the carotid
bodies. They respond to changes in blood CO2 and O2
levels, but are much more sensitive to carbon dioxide than
oxygen.
CHAPTER 9. DIGESTIVE SYSTEM
LONG ESSAYS (10M)

1. Draw a neat diagram of GI tract. Explain how fats
are digested and absorbed.
Answer: Lipid (fat) digestion begins in the stomach with
the aid of lingual lipase and gastric lipase. However, the
bulk of lipid digestion occurs in the small intestine due to
pancreatic lipase. When chyme enters the duodenum, the
hormonal responses trigger the release of bile, which is
produced in the liver and stored in the gallbladder. Bile
aids in the digestion of lipids, primarily triglycerides,
through emulsification. Emulsification is a process in
which large lipid globules are broken down into several
small lipid globules. These small globules are widely
distributed in the chyme rather than forming large
aggregates. Lipids are hydrophobic substances. Bile
contains bile salts, which have hydrophobic and hydrophilic sides. The bile salts' hydrophilic side can
interface with water, while the hydrophobic side interfaces with lipids, thereby emulsifying large lipid
globules into small lipid globules.
Emulsification is important for the digestion of lipids because lipases can only efficiently act on the lipids
when they are broken into small aggregates. Lipases break down the lipids into fatty acids and glycerides.
These molecules can pass through the plasma membrane of the cell, entering the epithelial cells of the
intestinal lining. The bile salts surround long-chain fatty acids and monoglycerides, forming tiny spheres
ELNAZ. Z 39
called micelles. The micelles move into the brush border of the small intestine absorptive cells where the
long-chain fatty acids and monoglycerides diffuse out of the micelles into the absorptive cells, leaving the
micelles behind in the chyme. The long-chain fatty acids and monoglycerides recombine in the absorptive
cells to form triglycerides, which aggregate into globules, and are then coated with proteins. These large
spheres are called chylomicrons. Chylomicrons contain triglycerides, cholesterol, and other lipids; they
have proteins on their surface. The surface is also composed of the hydrophilic phosphate "heads" of
phospholipids. Together, they enable the chylomicron to move in an aqueous environment without exposing
the lipids to water. Chylomicrons leave the absorptive cells via exocytosis, entering the lymphatic vessels.
From there, they enter the blood in the subclavian vein .
2. Describe the gross anatomy of stomach. Explain its physiological functions.

Answer: The stomach is continuous with the oesophagus at the cardiac sphincter and with the duodenum
at the pyloric sphincter. It has two curvatures. The lesser curvature is short, lies on the posterior surface of
the stomach and is the downward continuation of the posterior wall of the oesophagus. Just before the
pyloric sphincter it curves upwards to complete the J shape. Where the oesophagus joins the stomach the
anterior region angles acutely upwards, curves downwards forming the greater curvature and then slightly
upwards towards the pyloric sphincter.
The stomach is divided into three regions: the fundus, the body and the pylorus. At the distal end of the
pylorus is the pyloric sphincter, guarding the opening between the stomach and the duodenum. When the
stomach is inactive the pyloric sphincter is relaxed and open, and when the stomach contains food the
sphincter is closed.
Functions of the stomach
These include:
• Temporary storage allowing time for the digestive enzymes, pepsins, to act.
• Chemical digestion – pepsins break proteins into polypeptides.
• Mechanical breakdown – the three smooth muscle layers enable the stomach to act as a churn, gastric
juice is added and the contents are liquefied to chyme. Gastric motility and secretion are increased by
parasympathetic nerve stimulation.
• Limited absorption – water, alcohol and some lipid soluble drugs.
• Nonspecific defence against microbes – provided by hydrochloric acid in gastric juice. Vomiting may
occur in response to ingestion of gastric irritants, e.g. microbes or chemicals.
• Preparation of iron for absorption – the acid environment of the stomach solubilises iron salts, essential
for iron absorption in the small intestine.
• Production and secretion of intrinsic factor needed for absorption of vitamin B12 in the terminal ileum.
• Regulation of the passage of gastric contents into the duodenum. When the chyme is sufficiently acidified
and liquefied, the pylorus forces small jets of gastric contents through the pyloric sphincter into the
duodenum. The sphincter is normally closed, preventing backflow of chyme into the stomach.
• Secretion of the hormone gastrin.
3. Write the anatomy of pancreas. Discuss the endocrine and exocrine secretions of pancreas.
Answer: It is about 12–15 cm long and is situated in the epigastric and left hypochondriac regions of the
abdominal cavity. It consists of a broad head, a body and a narrow tail. The head lies in the curve of the
duodenum, the body behind the stomach and the tail lies in front of the left kidney and just reaches the
spleen. The abdominal aorta and the inferior vena cava lie behind the gland. The pancreas is both an
exocrine and endocrine gland.
The exocrine pancreas
This consists of a large number of lobules made up of small acini, the walls of which consist of secretory
cells. Each lobule is drained by a tiny duct and these unite eventually to form the pancreatic duct, which
extends along the whole length of the gland and opens into the duodenum. Just before entering the
duodenum the pancreatic duct joins the common bile duct to form the hepatopancreatic ampulla. The
duodenal opening of the ampulla is controlled by the hepatopancreatic sphincter (of Oddi) at the duodenal
papilla. The function of the exocrine pancreas is to produce pancreatic juice containing enzymes, some in
the form of inactive precursors, that digest carbohydrates, proteins and fats. As in the alimentary tract,
parasympathetic stimulation increases the secretion of pancreatic juice and sympathetic stimulation
depresses it.
The endocrine pancreas
ELNAZ. Z 40
Distributed throughout the gland are groups of specialised cells called the pancreatic islets (of Langerhans).
The islets have no ducts so the hormones diffuse directly into the blood. The endocrine pancreas secretes
the hormones insulin and glucagon, which are principally concerned with control of blood glucose levels.
4. Describe the anatomy, histology and functions of small intestine and stomach.
Answer: [FOR STOMACH REFER QUESTION NO.2]
The small intestine is continuous with the stomach at the pyloric sphincter. The small intestine is about 2.5
cm in diameter, a little over 5 metres long and leads into the large intestine at the ileocaecal valve. It lies
in the abdominal cavity surrounded by the large intestine. In the small intestine, the chemical digestion of
food is completed and absorption of most nutrients takes place. The small intestine comprises three
continuous parts.
Duodenum. This is about 25 cm long and curves around the head of the pancreas. Secretions from the gall
bladder and pancreas merge in a common structure – the hepatopancreatic ampulla – and enter the
duodenum at the duodenal papilla. The duodenal papilla is guarded by a ring of smooth muscle, the
hepatopancreatic sphincter (of Oddi).
Jejunum. This is the middle section of the small intestine and is about 2 metres long.
Ileum. This terminal section is about 3 metres long and ends at the ileocaecal valve, which controls the
flow of material from the ileum to the caecum, the first part of the large intestine, and prevents backflow.
Histology of small intestine
Peritoneum
The mesentery, a double layer of peritoneum, attaches the jejunum and ileum to the posterior abdominal
wall. The attachment is quite short in comparison with the length of the small intestine, therefore it is fan
shaped. The large blood vessels and nerves lie on the posterior abdominal wall and the branches to the
small intestine pass between the two layers of the mesentery.
Mucosa
The surface area of the small intestine mucosa is greatly increased by permanent circular folds, villi and
microvilli. The permanent circular folds, unlike the rugae of the stomach, are not smoothed out when the
small intestine is distended. They promote mixing of chyme as it passes along. The villi are tiny finger like
projections of the mucosal layer into the intestinal lumen, about 0.5–1 mm long. Their covering consists of
columnar epithelial cells, or enterocytes, with tiny microvilli (1 μm long) on their free border. Goblet cells
that secrete mucus are interspersed between the enterocytes. These epithelial cells enclose a network of
blood capilliaries and a central lymph capillary. Lymph capillaries are called lacteals because absorbed fat
gives the lymph a milky appearance. Absorption and some final stages of digestion of nutrients take place
in the enterocytes before entering the blood and lymph capillaries.
Functions of the small intestine
The functions are:
• Onward movement of its contents by peristalsis, which is increased by parasympathetic stimulation.
• Secretion of intestinal juice, also increased by parasympathetic stimulation.
• Completion of chemical digestion of carbohydrates, protein and fats in the enterocytes of the villi.
• Protection against infection by microbes that have survived the antimicrobial action of the hydrochloric
acid in the stomach, by both solitary and aggregated lymph follicles.
• Secretion of the hormones cholecystokinin (CCK) and secretin.
• Absorption of nutrients.
5. Explain how digestion of carbohydrates, proteins and fats takes place.

Answer: Digestion of Carbohydrates
The digestion of carbohydrates begins in the mouth. The salivary enzyme amylase begins the breakdown
of food starches into maltose, a disaccharide. As the food travels through the esophagus to the stomach, no
significant digestion of carbohydrates takes place. The acidic environment in the stomach stops amylase
from continuing to break down the molecules.
The next step of carbohydrate digestion takes place in the duodenum. The chyme from the stomach enters
the duodenum and mixes with the digestive secretions from the pancreas, liver, and gallbladder. Pancreatic
juices also contain amylase, which continues the breakdown of starch and glycogen into maltose and other
disaccharides. These disaccharides are then broken down into monosaccharides by enzymes called
maltases, sucrases, and lactases. The monosaccharides produced are absorbed so that they can be used in
ELNAZ. Z 41
metabolic pathways to harness energy. They are absorbed across the intestinal epithelium into the
bloodstream to be transported to the different cells in the body.
Digestion of Proteins
A large part of protein digestion takes place in the stomach. The enzyme pepsin plays an important role in
the digestion of proteins by breaking them down into peptides, short chains of four to nine amino acids. In
the duodenum, other enzymes – trypsin, elastase, and chymotrypsin – act on the peptides, reducing them to
smaller peptides. These enzymes are produced by the pancreas and released into the duodenum where they
also act on the chyme. Further breakdown of peptides to single amino acids is aided by enzymes called
peptidases (those that break down peptides). The amino acids are absorbed into the bloodstream through
the small intestine.
Digestion of fats refer question no.1 (10M)
6. Describe the anatomy of liver and mention its functions.

Answer: The lobes of the liver are made up of tiny functional units, called lobules, which are just visible
to the naked eye. Liver lobules are hexagonal in outline and are formed by cuboidal cells, the hepatocytes,
arranged in pairs of columns radiating from a central vein. Between two pairs of columns of cells are
sinusoids (blood vessels with incomplete walls) containing a mixture of blood from the tiny branches of
the portal vein and hepatic artery. This arrangement allows the arterial blood and portal venous blood (with
a high concentration of nutrients) to mix and come into close contact with the liver cells. Amongst the cells
lining the sinusoids are hepatic macrophages (Kupffer cells) whose function is to ingest and destroy worn
out blood cells and any foreign particles present in the blood flowing through the liver. Blood drains from
the sinusoids into central or centrilobular veins. These then merge with veins from other lobules, forming
larger veins, until eventually they become the hepatic veins, which leave the liver and empty into the
inferior vena cava. One of the functions of the liver is to secrete bile. Bile canaliculi run between the
columns of liver cells. This means that each column of hepatocytes has a blood sinusoid on one side and a
bile canaliculus on the other. The canaliculi join up to form larger bile canals until eventually they form the
right and left hepatic ducts, which drain bile from the liver. Lymphoid tissue and a network of lymph
vessels are also present in each lobule.
Cleanses blood
• metabolizing alcohol and other drugs and chemicals,
• neutralizing and destroying poisonous substances.
Regulates the supply of body fuel
• producing, storing and supplying quick energy (glucose) to keep the mind alert and the body active,
producing, storing and exporting fat.
Manufactures many essential body proteins involved in
• transporting substances in the blood,
• clotting of blood,
• providing resistance to infection.
Regulates the balance of many hormones
• sex hormones,
• thyroid hormones,
• cortisone and other adrenal hormones.
Regulates body cholesterol
• produces cholesterol, excretes and converts it to other essential substances.
Regulates the supply of essential vitamins and minerals such as iron and copper.
Produces bile which eliminates toxic substances from the body and aids digestion.
SHORT ESSAYS (5M)

1. List out the various enzymes present in the secretions of GIT.
ELNAZ. Z 42
Answer:
2. Write composition and functions of gastric juice.

Answer: Composition of gastric juice
• Water
• Mineral salts
• Mucus secreted by mucous neck cells in the glands and surface mucous cells on the stomach surface
• Hydrochloric acid
• Intrinsic factor
• Inactive enzyme precursors: pepsinogens secreted by chief cells in the glands.
Functions of gastric juice
• Water further liquefies the food swallowed.
• Hydrochloric acid:
– acidifies the food and stops the action of salivary amylase
– kills ingested microbes
– provides the acid environment needed for the action of pepsins.
• Pepsinogens are activated to pepsins by hydrochloric acid and by pepsins already present in the stomach.
These enzymes begin the digestion of proteins, breaking them into smaller molecules. Pepsins have evolved
to act most effectively at a very low pH, between 1.5 and 3.5.
• Intrinsic factor (a protein) is necessary for the absorption of vitamin B12 from the ileum. (Deficiency
leads to pernicious anemia.)
• Mucus prevents mechanical injury to the stomach wall by lubricating the contents. It also prevents
chemical injury by acting as a barrier between the stomach wall and the corrosive gastric juice –
ELNAZ. Z 43
hydrochloric acid is present in potentially damaging concentrations and pepsins would digest the gastric
tissues.
3. Name salivary glands and discuss the composition and functions of saliva.
Answer: There are three main pairs: the parotid glands, the submandibular glands and the sublingual
glands.
Composition of saliva.
About 1.5 litres of saliva is produced daily and
it consists of:
• Water
• Mineral salts
• Salivary amylase; a digestive enzyme
• Mucus
• Antimicrobial substances; immunoglobulins and the enzyme lysozyme.
Functions of saliva.
Chemical digestion of polysaccharides
• Saliva contains the enzyme amylase that begins the breakdown of complex sugars, including
starches, reducing them to the disaccharide maltose.
Lubrication of food
• The high-water content means that dry food entering the mouth is moistened and lubricated by
saliva before it can be made into a bolus ready for swallowing.
Cleaning and lubricating the mouth
• An adequate flow of saliva is necessary to clean the mouth, and to keep it soft, moist and pliable.
This helps
• to prevent damage to the mucous membrane by rough or abrasive food.
Non-specific defence
• Lysozyme and immunoglobulins present in saliva combat invading microbes.
Taste
• The taste buds are stimulated only by chemical substances in solution and therefore dry foods only
stimulate the sense of taste after thorough mixing with saliva. The senses of taste and smell are
closely linked and involved in the enjoyment, or otherwise, of food.
4. Discuss the digestion of carbohydrates.

Answer: Refer Question No.5 (10M)
5. Discuss the food absorption in small intestine.

Answer: Absorption of foods from the small intestine through the enterocytes occurs by several processes,
including diffusion, osmosis, facilitated diffusion and active transport. Water moves by osmosis; small fat
soluble substances, e.g. fatty acids and glycerol, are able to diffuse through cell membranes; while others
are generally transported inside the villi by other mechanisms.
Monosaccharides and amino acids pass into the blood capillaries in the villi. Fatty acids and glycerol enter
the lacteals and are transported along lymphatic vessels to the thoracic duct where they enter the circulation.
A small number of proteins are absorbed unchanged, e.g. antibodies present in breast milk and oral
vaccines, such as poliomyelitis vaccine. Other nutrients such as vitamins, mineral salts and water are also
absorbed from the small intestine into the blood capillaries.
Fat soluble vitamins are absorbed into the lacteals along with fatty acids and glycerol. Vitamin B12
combines with intrinsic factor in the stomach and is actively absorbed in the terminal ileum. The surface
area through which absorption takes place in the small intestine is greatly increased by the circular folds of
mucous membrane and by the very large number of villi and microvilli present. It has been calculated that
the surface area of the small intestine is about five times that of the whole body surface. Large amounts of
fluid enter the alimentary tract each day. Of this, only about 1500 mL is not absorbed by the small intestine,
and passes into the large intestine.
ELNAZ. Z 44
6. Describe the functions of liver.
Answer: • Carbohydrate metabolism. The liver is especially important in maintaining a normal blood
glucose level. When blood glucose is low, the liver can break down glycogen to glucose and release the
glucose into the bloodstream. The liver can also convert certain amino acids and lactic acid to glucose.
• Lipid metabolism. Hepatocytes store some triglycerides; break down fatty acids to generate ATP;
synthesize lipoproteins, which transport fatty acids, triglycerides, and cholesterol to and from body cells;
synthesize cholesterol; and use cholesterol to make bile salts.
• Protein metabolism. Hepatocytes deaminate (remove the amino group, NH2, from) amino acids so that
the amino acids can be used for ATP production or converted to carbohydrates or fats. The resulting toxic
ammonia (NH3) is then converted into the much less toxic urea, which is excreted in urine.
• Processing of drugs and hormones. The liver can detoxify substances such as alcohol and excrete drugs
such as penicillin, erythromycin, and sulfonamides into bile. It can also chemically alter or excrete thyroid
hormones and steroid hormones such as estrogens and aldosterone.
• Excretion of bilirubin. As previously noted, bilirubin, derived from the heme of aged red blood cells, is
absorbed by the liver from the blood and secreted into bile. Most of the bilirubin in bile is metabolized in
the small intestine by bacteria and eliminated in feces.
• Synthesis of bile salts. Bile salts are used in the small intestine for the emulsification and absorption of
lipids.
• Storage. In addition to glycogen, the liver is a prime storage site for certain vitamins (A, B12, D, E, and
K) and minerals (iron and copper), which are released from the liver when needed elsewhere in the body.
• Phagocytosis. The stellate reticuloendothelial (Kupffer) cells of the liver phagocytize aged red blood cells,
white blood cells, and some bacteria.
• Activation of vitamin D. The skin, liver, and kidneys participate in synthesizing the active form of vitamin
D.
7. Describe the digestion in small intestine.

Answer: Digestion of proteins. Trypsinogen and chymotrypsinogen are inactive enzyme precursors
activated by enterokinase, an enzyme in the microvilli, which converts them into the active proteolytic
enzymes trypsin and chymotrypsin. These enzymes convert polypeptides to tripeptides, dipeptides and
amino acids. It is important that they are produced as inactive precursors and are activated only upon their
arrival in the duodenum, otherwise they would digest the pancreas.
Digestion of carbohydrates. Pancreatic amylase converts all digestible polysaccharides (starches) not
acted upon by salivary amylase to disaccharides.
Digestion of fats. Lipase converts fats to fatty acids and glycerol. To aid the action of lipase, bile salts
emulsify fats, i.e. reduce the size of the globules, increasing their surface area.
8. Explain how digestion takes place in stomach.

Answer:
ELNAZ. Z 45
9. Write the exocrine functions of pancreas.
Answer: The exocrine pancreas
This consists of a large number of lobules made up of small acini, the walls of which consist of secretory
cells. Each lobule is drained by a tiny duct and these unite eventually to form the pancreatic duct, which
extends along the whole length of the gland and opens into the duodenum. Just before entering the
duodenum the pancreatic duct joins the common bile duct to form the hepatopancreatic ampulla. The
duodenal opening of the ampulla is controlled by the hepatopancreatic sphincter (of Oddi) at the duodenal
papilla. The function of the exocrine pancreas is to produce pancreatic juice containing enzymes, some in
the form of inactive precursors, that digest carbohydrates, proteins and fats. As in the alimentary tract,
parasympathetic stimulation increases the secretion of pancreatic juice and sympathetic stimulation
depresses it.
SHORT ANSWERS (2M)

1. Name digestive enzymes.
Answer: Refer Question No. 1 (5M)
2. Give functions of bile.

Answer: Emulsify fats and break it down into small particles. This is a detergent-like action of bile.
ELNAZ. Z 46
Helps the body absorb the breakdown products of fat in the gut. Bile salts bind with lipids to form micelles.
This is then absorbed through the intestinal mucosa.
3. Write exocrine functions of pancreas

4. What do mean by peptic ulcer

Answer: Peptic ulcer or Stomach ulcer, is a break in the lining of the stomach, first part of the small
intestine, or occasionally the lower esophagus. Common causes include the bacteria Helicobacter
pylori and non-steroidal anti-inflammatory drugs (NSAIDs).
5. Draw a neat labelled diagram of stomach

Answer:
6. Name the salivary glands and functions of their secretions.

7. Explain peristaltic movement of small intestine.

Answer: Peristalsis, which is a wavelike series of muscular contractions. You might recall that peristalsis
is also how food moves through your esophagus as it travels from the throat to the stomach. During
peristalsis, the longitudinal muscles within the small intestine wall contract, and then the circular muscles
contract, pushing the food down the tract. This coordinated contraction of smooth muscle keeps food
moving on its one-way path through your digestive system.
8. Mention the functions of pancreatic enzymes.
Answer: Pancreatic enzymes help break down fats, proteins and carbohydrates. A normally functioning
pancreas secretes about 8 cups of pancreatic juice into the duodenum, daily. This fluid contains pancreatic
enzymes to help with digestion and bicarbonate to neutralize stomach acid as it enters the small intestine.
9. Write the composition of bile.

Answer: Between 500 and 1000 mL of bile is secreted by the liver daily. Bile consists of:
• water
• mineral salts
• mucus
• bile pigments, mainly bilirubin
• bile salts
• cholesterol.
10. Mention the functions of stomach.
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11.What is liver cirrhosis?

Answer: Chronic liver damage results in inflammation, necrosis and, in time, affected tissue is replaced
with fibrous tissue. Hyperplasia of hepatocytes occurs in areas adjacent to the damaged tissue in an attempt
to compensate for destroyed cells, which leads to formation of nodules. The normal structure of the liver
lobules becomes increasingly abnormal, usually over several years, which interferes with blood flow
resulting in portal hypertension and its consequences, and impairment of liver cell function.
CHAPTER 10. NERVOUS SYSTEM
LONG ESSAYS (10M)

1. Describe the structure and functional areas of cerebrum.
Answer: This is the largest part of the brain and
it occupies the anterior and middle cranial
fossae. It is divided by a deep cleft, the
longitudinal cerebral fissure, into right and left
cerebral hemispheres, each containing one of
the lateral ventricles. Deep within the brain, the
hemispheres are connected by a mass of white
matter (nerve fibres) called the corpus
callosum.
The falx cerebri is formed by the dura mater. It
separates the two cerebral hemispheres and
penetrates to the depth of the corpus callosum.
The superficial part of the cerebrum is
composed of nerve cell bodies (grey matter),
forming the cerebral cortex, and the deeper layers consist of nerve fibres (axons, white matter). The cerebral
cortex shows many infoldings or furrows of varying depth. The exposed areas of the folds are the gyri
(convolutions) and these are separated by sulci (fissures). These convolutions greatly increase the surface
area of the cerebrum.
Functions of the cerebral cortex
There are three main types of activity associated with the cerebral cortex:
• Higher order functions, i.e. the mental activities involved in memory, sense of responsibility, thinking,
reasoning, moral decision making and learning
• Sensory perception, including the perception of pain, temperature, touch, sight, hearing, taste and smell
• Initiation and control of skeletal muscle contraction and therefore voluntary movement.
Functional areas of the cerebral cortex
The main functional areas of the cerebral cortex have been identified but it is unlikely that any area is
associated exclusively with only one function. Except where specially mentioned, the different areas are
active in both hemispheres; however, there is some variation between individuals. There are different types
of functional area:
• Motor, which direct skeletal (voluntary) muscle movements
• Sensory, which receive and decode sensory impulses enabling sensory perception
• Association, which are concerned with integration and processing of complex mental functions such as
intelligence, memory, reasoning, judgement and emotions.
In general, areas of the cortex lying anterior to the central sulcus are associated with motor functions, and
those lying posterior to it are associated with sensory functions.
2. Describe the origination and functions of autonomic nervous system.

Answer: The autonomic or involuntary part of the nervous system controls involuntary body functions.
Although stimulation does not occur voluntarily, the individual can sometimes be conscious of its effects,
e.g. an increase in their heart rate. The autonomic nervous system is separated into two divisions:
• Sympathetic (thoracolumbar outflow)
• Parasympathetic (craniosacral outflow)
ELNAZ. Z 48
The two divisions work in an integrated and complementary manner to maintain involuntary functions and
homeostasis. Such activities include coordination and control of breathing, blood pressure, water balance,
digestion and metabolic rate. Sympathetic activity predominates in stressful situations as it equips the body
to respond when exertion and exercise is required. Parasympathetic activity is increased (and sympathetic
activity is normally lessened) when digestion and restorative body activities predominate. There are
similarities and differences between the two divisions.
The effects of autonomic activity are rapid. The effector organs are:
• smooth muscle, which controls the diameter of smaller airways and blood vessels
• cardiac muscle, which controls the rate and force of cardiac contraction
• glands that control the volumes of gastrointestinal secretions.
The efferent (motor) nerves of the autonomic nervous system arise from the brain and emerge at various
levels between the midbrain and the sacral region of the spinal cord. Many of them travel within the same
nerve sheath as peripheral nerves to reach the organs they innervate. Each division has two efferent
neurones between the central nervous system and effector organs. These are:
• The preganglionic neurone
• The postganglionic neurone.
The cell body of the preganglionic neurone is in the brain or spinal cord. Its axon terminals synapse with
the cell body of the postganglionic neurone in an autonomic ganglion outside the CNS. The postganglionic
neurone conducts impulses to the effector organ.
Functions of ANS
Sympathetic nervous system - Promotes a fight-or-flight response, corresponds with arousal and energy
generation, and inhibits digestion.
• Diverts blood flow away from the gastro-intestinal (GI) tract and skin via vasoconstriction
• Blood flow to skeletal muscles and the lungs is enhanced (by as much as 1200% in the case of skeletal
muscles)
• Dilates bronchioles of the lung through circulating epinephrine, which allows for greater alveolar
oxygen exchange
• Increases heart rate and the contractility of cardiac cells (myocytes), thereby providing a mechanism
for enhanced blood flow to skeletal muscles
• Dilates pupils and relaxes the ciliary muscle to the lens, allowing more light to enter the eye and
enhances far vision
• Provides vasodilation for the coronary vessels of the heart
• Constricts all the intestinal sphincters and the urinary sphincter
• Inhibits peristalsis
• Stimulates orgasm
Parasympathetic nervous system - The parasympathetic nervous system has been said to promote a
"rest and digest" response, promotes calming of the nerves return to regular function, and enhancing
digestion. Functions of nerves within the parasympathetic nervous system include:
• Dilating blood vessels leading to the GI tract, increasing blood flow (this is important following the
consumption of food, due to the greater metabolic demands placed on the body by the gut)
• Constricting the bronchiolar diameter when the need for oxygen has diminished
• Dedicated cardiac branches of the vagus and thoracic spinal accessory nerves impart parasympathetic
control of the heart (myocardium)
• Constriction of the pupil and contraction of the ciliary muscles, facilitating accommodation and
allowing for closer vision
• Stimulating salivary gland secretion, and accelerates peristalsis, mediating digestion of food and,
indirectly, the absorption of nutrients
• Sexual. Nerves of the peripheral nervous system are involved in the erection of genital tissues via
the pelvic splanchnic nerves 2–4. They are also responsible for stimulating sexual arousal.
Neurotransmitters - At the effector organs, sympathetic ganglionic neurons
release noradrenaline (norepinephrine), along with other cotransmitters such as ATP, to act on adrenergic
receptors, with the exception of the sweat glands and the adrenal medulla:
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• Acetylcholine is the preganglionic neurotransmitter for both divisions of the ANS, as well as the
postganglionic neurotransmitter of parasympathetic neurons. Nerves that release acetylcholine are said
to be cholinergic. In the parasympathetic system, ganglionic neurons use acetylcholine as a
neurotransmitter to stimulate muscarinic receptors.
• At the adrenal medulla, there is no postsynaptic neuron. Instead the presynaptic neuron releases
acetylcholine to act on nicotinic receptors. Stimulation of the adrenal medulla
releases adrenaline (epinephrine) into the bloodstream, which acts on adrenoceptors, producing a
widespread increase in sympathetic activity.
3. Define Sympathetic and Parasympathetic system and discuss their anatomical and physiological
differences.
Answer: The autonomic nervous system has two branches: the sympathetic nervous system and
the parasympathetic nervous system. The sympathetic nervous system is often considered the "fight or
flight" system, while the parasympathetic nervous system is often considered the "rest and digest" or "feed
and breed" system. In many cases, both of these systems have "opposite" actions where one system activates
a physiological response and the other inhibits it.
4. Explain the functions of different cranial nerves.

Answer:
SL.NO. CRANIAL NERVE FUNCTION
1 Olfactory nerve Smell.
2 Optic Nerve Vision.

Somatic motor function: Movement
3 Oculomotor nerve
of upper eyelid and eyeball.
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Autonomic motor function
(parasympathetic): Accommodation
of lens for near vision and
constriction of pupil.
Somatic motor function: Movement of
4 Trochlear nerve
the eyeball.
Sensory function: Conveys impulses
for touch, pain, and temperature
5 Trigeminal nerve
sensations and proprioception.
Somatic motor function: Chewing.
6 Abducens nerve Movement of the eyeball.
Sensory function: Touch, pain, and
temperature sensations,
proprioception, and taste.
Somatic motor function: Facial
7 Facial nerve
expression.
(parasympathetic): Secretion of
saliva and tears.
Vestibular branch function: Conveys
impulses related to equilibrium.
8 Vestibulocochlear nerve
Cochlear branch function: Conveys
impulses for hearing.
Sensory function: Taste and somatic
sensations (touch, pain, temperature)
from posterior third of tongue;
proprioception in swallowing
muscles; monitoring of blood
pressure; monitoring of O2 and CO2
in blood for regulation of breathing
9 Glossopharyngeal nerve
rate and depth.
Somatic motor function: Elevates the
pharynx during swallowing and
speech.
(parasympathetic): Stimulates
secretion of saliva.
Sensory function: Taste and somatic
sensations (touch, pain, temperature,
and proprioception) from epiglottis
and pharynx; monitoring of blood
pressure; monitoring of O2 and CO2
in blood for regulation of breathing
rate and depth; sensations from
visceral organs in thorax and
10 Vagus nerve
abdomen.
Somatic motor function: Swallowing,
coughing, and voice production.
(parasympathetic): Smooth muscle
contraction and relaxation in organs
of the GI tract; slowing of the heart
rate; secretion of digestive fluids.
Mediates movement of head and
11 Accessory nerve
pectoral girdle.
Movement of tongue during speech
12 Hypoglossal nerve
and swallowing.
5. Name the divisions of CNS and explain the functions of hypothalamus and cerebrum.
Answer:
ELNAZ. Z 51
Hypothalamus: Controls and
integrates activities of the autonomic
nervous system. Produces hormones,
including releasing homones,
inhibiting hormones, oxytocin, and
ADH. Regulates emotional and
behavioral patterns (together with the
limbic system). Contains a feeding
center and satiety center, which
regulate eating. Contains a thirst
center, which regulates drinking.
Controls body temperature by serving
as the body’s thermostat. Contains a
suprachiasmatic nucleus that regulates
circadian rhythms.
Cerebrum: Sensory areas of the
cerebral cortex are involved in the
perception of sensory information;
motor areas of the cerebral cortex
control the execution of voluntary movements; and association areas of the cerebral cortex deal with more
complex integrative functions such as memory, personality traits, and intelligence. Basal ganglia help
initiate and terminate movements, suppress unwanted movements, and regulate muscle tone. The limbic
system promotes a range of emotions, including pleasure, pain, docility, affection, fear, and anger.
SHORT ESSAYS (5M)

1. Mention the anatomical location and functions of the following structures:
a). Basal ganglia. b). Thalamus.
Answer: Basal ganglia: The basal ganglia are groups of cell bodies that lie deep within the brain and form
part of the extrapyramidal tracts. They act as relay stations with connections to many parts of the brain
including motor areas of the cerebral cortex and thalamus. Their functions include initiation and fine control
of complex movement and learned coordinated activities, such as posture and walking. If control is
inadequate or absent, movements are jerky, clumsy and uncoordinated.
Thalamus
This consists of two masses of grey and white matter situated within the cerebral hemispheres just below
the corpus callosum, one on each side of the third ventricle. Sensory receptors in the skin and viscera send
information about touch, pain and temperature, and input from the special sense organs travels to the
thalamus where there is recognition, although only in a basic form, as refined perception also involves other
parts of the brain. It is thought to be involved in the processing of some emotions and complex reflexes.
The thalamus relays and redistributes impulses from most parts of the brain to the cerebral cortex.
2. What are the functions of medulla oblongata and pons.

Answer: Medulla oblongata: Contains sensory (ascending) tracts and motor (descending) tracts. The
cardiovascular center regulates heartbeat and blood vessel diameter. The medullary rhythmicity area
regulates breathing (together with pons). Contains the gracile nucleus, cuneate nucleus, gustatory nucleus,
cochlear nuclei, and vestibular nuclei, which are components of sensory pathways to the brain. The inferior
olivary nucleus provides instructions that the cerebellum uses to adjust muscle activity when learning new
motor skills. Other nuclei coordinate vomiting, swallowing, sneezing, coughing, and hiccupping. Contains
nuclei of origin for cranial nerves VIII, IX, X, XI, and XII. Reticular formation (also in pons, midbrain, and
diencephalon) functions in consciousness and arousal.
Pons: Contains sensory tracts and motor tracts. Pontine nuclei relay nerve impulses from motor areas of
cerebral cortex to cerebellum. Contains vestibular nuclei (along with medulla) that are part of equilibrium
pathway to the brain. Pneumotaxic area and apneustic area help control breathing (together with the
medulla). Contains nuclei of origin for cranial nerves V, VI, VII, and VIII.
3. Describe the meninges and ventricles in the brain?

ELNAZ. Z 52
Answer: The brain and spinal cord are completely surrounded by three layers of tissue, the meninges, lying
between the skull and the brain, and between the vertebral foramina and the spinal cord. Named from
outside inwards they are the:
• dura mater
• arachnoid mater
• pia mater.
The dura and arachnoid maters are separated by a potential space, the subdural space. The arachnoid and
pia maters are separated by the subarachnoid space, containing cerebrospinal fluid.
Dura mater: It is composed of dense, irregular connective tissue. It forms a sac from the level of the
foramen magnum in the occipital bone, where it is continuous with the dura mater of the brain, to the second
sacral vertebra. The spinal cord is also protected by a cushion of fat and connective tissue located in the
epidural space, a space between the dura mater and the wall of the vertebral canal. The middle meninx
(singular form of meninges) is an avascular covering called the arachnoid mater because of its spider’s
web arrangement of delicate collagen fibers and some elastic fibers. It is deep to the dura mater and is
continuous with the arachnoid mater of the brain. Between the dura mater and the arachnoid mater is a thin
subdural space, which contains interstitial fluid. The innermost meninx is the pia mater, a thin transparent
connective tissue layer that adheres to the surface of the spinal cord and brain. It consists of squamous to
cuboidal cells within interlacing bundles of collagen fibers and some fine elastic fibers. Within the pia
mater are many blood vessels that supply oxygen and nutrients to the spinal cord. Between the arachnoid
mater and the pia mater is the subarachnoid space, which contains cerebrospinal fluid that serves as a
shock absorber and suspension system for the spinal cord and brain.
The four CSF-filled cavities within the brain, which are called ventricles. A lateral ventricle is located in
each hemisphere of the cerebrum. Anteriorly, the lateral ventricles are separated by a thin membrane, the
septum pellucidum. The third ventricle is a narrow cavity along the midline superior to the hypothalamus
and between the right and left halves of the thalamus. The fourth ventricle lies between the brain stem and
the cerebellum.
4. What are the functions of cerebellum?

Answer: The cerebellum is concerned with the coordination of voluntary muscular movement, posture and
balance. Cerebellar activity is not under voluntary control. The cerebellum controls and coordinates the
movements of various groups of muscles ensuring smooth, even, precise actions. It coordinates activities
associated with the maintenance of posture, balance and equilibrium. The sensory input for these functions
is derived from the muscles and joints, the eyes and the ears. Proprioceptor impulses from the muscles and
joints indicate their position in relation to the body as a whole; impulses from the eyes and the semicircular
canals in the ears provide information about the position of the head in space. The cerebellum integrates
this information to regulate skeletal muscle activity so that balance and posture are maintained.
The cerebellum may also have a role in learning and language processing. Damage to the cerebellum results
in clumsy uncoordinated muscular movement, staggering gait and inability to carry out smooth, steady,
precise movements.
5. Define reflex action with example.

Answer: A reflex action is an involuntary and immediate motor response to a sensory stimulus. Many
connector and motor neurones may be stimulated by afferent impulses from a small area of skin. For
example, the pain impulses initiated by touching a very hot surface with the finger are transmitted to the
spinal cord by sensory fibres in mixed nerves. These stimulate many connector and lower motor neurones
in the spinal cord, which results in the contraction of many skeletal muscles of the hand, arm and shoulder,
and the removal of the finger. Reflex action happens very quickly; in fact, the motor response may occur
simultaneously with the perception of the pain in the cerebrum.
6. Describe sympathetic outflow.

Answer: The sympathetic nervous system normally functions to produce localized adjustments (such
as sweating as a response to an increase in temperature) and reflex adjustments of the cardiovascular
system. Under conditions of stress, however, the entire sympathetic nervous system is activated, producing
an immediate, widespread response called the fight-or-flight response. This response is characterized by
the release of large quantities of epinephrine from the adrenal gland, an increase in heart rate, an increase
ELNAZ. Z 53
in cardiac output, skeletal
muscle vasodilation, cutaneous
and gastrointestinal
vasoconstriction, pupillary
dilation, bronchial dilation, and
piloerection. The overall effect
is to prepare the individual
for imminent danger.
7. Write effects of
parasympathetic stimulation.
Answer: Refer Question No.
3 (10M)
8. Define limbic system.

Explain several of its
functions.
Answer: Encircling the upper
part of the brain stem and the
corpus callosum is a ring of
structures on the inner border of
the cerebrum and floor of the
diencephalon that constitutes
the limbic system. The limbic
system is sometimes called the “emotional brain” because it plays a primary role in a range of emotions,
including pleasure, pain, docility, affection, fear, and anger. It also is involved in olfaction (smell) and
memory. Experiments have shown that when different areas of an animal’s limbic system are stimulated,
the animal’s reaction indicates extreme pleasure or intense pain.
9. Discuss the internal structure of spinal cord

Answer: The interior of the cord is formed by gray matter, which is surrounded by white matter. In
transverse sections, the gray matter is conventionally divided into dorsal (posterior) lateral
and ventral (anterior) “horns.” The neurons of the dorsal horns receive sensory information that enters the
spinal cord via the dorsal roots of the spinal nerves. The lateral horns are present primarily in the thoracic
region, and contain the preganglionic visceral motor neurons that project to the sympathetic ganglia. The
ventral horns contains the cell bodies of motor neurons that send axons via the ventral roots of the spinal
nerves to terminate on striated muscles. The white matter of the spinal cord is subdivided into dorsal (or
posterior), lateral, and ventral (or anterior) columns, each of which contains axon tracts related to specific
functions. The dorsal columns carry ascending sensory information from somatic mechanoreceptors.
The lateral columns include axons that travel from the cerebral cortex to contact spinal motor neurons.
ELNAZ. Z 54
10.Write the composition and functions of cerebro spinal fluid (CSF).
Answer: CSF is a clear, slightly alkaline fluid with a specific gravity of 1.005, consisting of:
• water
• mineral salts
• glucose
• plasma proteins: small amounts of albumin and globulin
• a few leukocytes
• creatinine
• urea
Functions of cerebrospinal fluid
CSF supports and protects the brain and spinal cord by maintaining a uniform pressure around these vital
structures and acting as a cushion or shock absorber between the brain and the skull. It keeps the brain and
spinal cord moist and there may be exchange of nutrients and waste products between CSF and the
interstitial fluid of the brain. CSF is thought to be involved in regulation of breathing as it bathes the surface
of the medulla where the central respiratory chemoreceptors are located.
SHORT ANSWERS (2M)

1. Draw and label schematic diagram of spinal reflex arc.
Answer:
2. Enumerate the functions of hypothalamus.

Answer: Hypothalamus: Controls and integrates activities of the autonomic nervous system. Produces
hormones, including releasing homones, inhibiting hormones, oxytocin, and ADH. Regulates emotional
ELNAZ. Z 55
and behavioral patterns (together with the limbic system). Contains a feeding center and satiety center,
which regulate eating. Contains a thirst center, which regulates drinking. Controls body temperature by
serving as the body’s thermostat. Contains a suprachiasmatic nucleus that regulates circadian rhythms.
3. Write main functions of cerebrospinal fluid.

Answer: Functions of cerebrospinal fluid
CSF supports and protects the brain and spinal cord by maintaining a uniform pressure around these vital
structures and acting as a cushion or shock absorber between the brain and the skull. It keeps the brain and
spinal cord moist and there may be exchange of nutrients and waste products between CSF and the
interstitial fluid of the brain. CSF is thought to be involved in regulation of breathing as it bathes the surface
of the medulla where the central respiratory chemoreceptors are located.
4. Give a brief account of CTZ (chemoceptor trigerzone).

Answer: The chemoreceptor trigger zone (CTZ) is an area of the medulla oblongata that receives inputs
from blood-borne drugs or hormones, and communicates with other structures in the vomiting center to
initiate vomiting. The CTZ is located within the area postrema, which is on the floor of the fourth
ventricle and is outside of the blood–brain barrier.[1] It is also part of the vomiting center itself.
5. Draw and label diagram of a neuron.

Answer:
6. What is a ganglion? Give its role in nervous system.

Answer: A ganglion is a nerve cell cluster or a group of nerve cell bodies located in the autonomic
nervous system and sensory system. Ganglia are closely associated with cranial and spinal nerves. In the
walls of organs of the gastrointestinal tract, extensive networks of neurons, called enteric plexuses, help
regulate the digestive system.
7. What is synaptic cleft? State its function.

Answer: The space between neurons at a nerve synapse across which a nerve impulse is transmitted by a
neurotransmitter. The synaptic cleft helps to decode the message. When the electrical signal reaches the
presynaptic ending, it is translated into a chemical message that then diffuses across the synaptic cleft to
ELNAZ. Z 56
the postsynaptic cell. The receiving neuron takes this information and translates the chemical message back
into electrical signals, which then heads into the next neuron where the process is repeated.
8. Classify nervous system.

Answer:
9. Name the ventricles present in the brain.

10. What is extra pyramidal tract.

Answer: The extrapyramidal tract is a biological neural network that is part of the motor system causing
involuntary movements. The system is called "extrapyramidal" to distinguish it from the tracts of the motor
cortex that reach their targets by traveling through the "pyramids" of the medulla. Extrapyramidal tracts are
chiefly found in the reticular formation of the pons and medulla, and target lower motor neurons in the
spinal cord that are involved in reflexes, locomotion, complex movements, and postural control.
11. Write the functions of olfactory and optic nerve.

CHAPTER 11. URINARY SYSTEM

LONG ESSAYS (10M)
1. Draw a neat, labelled diagram of nephron and describe how urine is formed?
Answer: There are three processes involved in the
formation of urine:
• Filtration
• Selective reabsorption
• Secretion.
Stage 1: Filtration. The kidney is the body's blood
filtering system. Blood vessels visit the kidney and enter
a special ball of capillaries called the glomerulus. The
glomerulus is nestled within a region of the kidney called
the Bowman's Capsule. This is where filtration occurs.
As blood is pushed through the tiny capillaries, the high-
pressure forces some things to pass through the capillary
walls. The walls act as a sieve or a filter. Hence, it is
called filtration.
Water, sugar, salts, amino acids, nitrogenous wastes, and
other tiny things enter the kidney as a substance called
ELNAZ. Z 57
the filtrate. Cells and large blood proteins that cannot fit through remain in the blood vessels. The filtrate
entering the kidney is like pre-pre-urine.
Stage 2: Reabsorption. The filtrate enters the kidney in the proximal tubule. This region of the kidney is
special because many things can be removed from the filtrate. These valuable things are recollected, or
reabsorbed, by the body.
Glucose, certain salts, vitamins, hormones, and amino acids are restored to the body and will not be
included in urine. Sometimes, if the body has too much of something then the extra sugar or salt will stay
in the filtrate. For example, diabetic with high levels of blood glucose may have glucose in their urine since
it cannot all be reabsorbed. The filtrate after reabsorption is like pre-urine.
Stage 3: Tubular secretion. Filtration occurs as blood flows through the glomerulus. Substances not
required and foreign materials, e.g. drugs including penicillin and aspirin, may not be entirely filtered out
of the blood because of the short time it remains in the glomerulus. Such substances are cleared by secretion
from the peritubular capillaries into the filtrate within the convoluted tubules. Tubular secretion of hydrogen
ions (H+) is important in maintaining normal blood pH.
2. Describe the structure of kidney and explain its functions.

Answer: The kidneys are two bean-shaped
organs that extract waste from blood, balance
body fluids, form urine, and aid in other
important functions of the body.
They reside against the back muscles in the
upper abdominal cavity. They sit opposite each
other on either side of the spine. The right kidney
sits a little bit lower than the left to accommodate
the liver.
When it comes to components of the urinary
system, the kidneys are multi-functional
powerhouses of activity. Some of the core
actions of the kidneys include:
A. Waste excretion: There are many things
your body doesn’t want inside of it. The
kidneys filter out toxins, excess salts,
and urea, a nitrogen-based waste created
by cell metabolism. Urea is synthesized
in the liver and transported through the blood to the kidneys for removal.
B. Water level balancing: As the kidneys are key in the chemical breakdown of urine, they react to
changes in the body’s water level throughout the day. As water intake decreases, the kidneys adjust
accordingly and leave water in the body instead of helping excrete it.
C. Blood pressure regulation: The kidneys need constant pressure to filter the blood. When it drops
too low, the kidneys increase the pressure. One way is by producing a blood vessel-constricting
protein (Renin-angiotensin) that also signals the body to retain sodium and water. Both the
constriction and retention help restore normal blood pressure.
D. Red blood cell regulation: When the kidneys don’t get enough oxygen, they send out a distress
call in the form of erythropoietin, a hormone that stimulates the bone marrow to produce more
oxygen-carrying red blood cells.
E. Acid regulation: As cells metabolize, they produce acids. Foods we eat can either increase the acid
in our body or neutralize it. If the body is to function properly, it needs to keep a healthy balance of
these chemicals. The kidneys do that, too.
SHORT ESSAYS (5M)

1. Write a note on Renin-Angiotensin-aldosterone system.
Answer: Sodium is a normal constituent of urine and its excretion is regulated by the hormone aldosterone,
secreted by the adrenal cortex. Cells in the afferent arteriole of the nephron release the enzyme renin in
response to sympathetic stimulation, low blood volume or by low arterial blood pressure. Renin converts
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the plasma protein angiotensinogen, produced by the liver, to angiotensin 1. Angiotensin converting enzyme
(ACE), formed in small quantities in the lungs, proximal convoluted tubules and other tissues, converts
angiotensin 1 into angiotensin 2, which is a very potent vasoconstrictor and increases blood pressure.
Renin and raised blood potassium levels also stimulate the adrenal gland to secrete aldosterone. Water is
reabsorbed with sodium and together they increase the blood volume, which reduces renin secretion through
the negative feedback mechanism. When sodium reabsorption is increased potassium excretion is
increased, indirectly reducing intracellular potassium. Profound diuresis may lead to hypokalaemia (low
blood potassium levels).
2. Write the structure of nephron with neat labeled diagram

3. Role of kidney in maintaining acid-base balance.

Answer: In order to maintain normal blood pH (acid–base balance), the proximal convoluted tubules
secrete hydrogen ions into the filtrate where they combine with buffers:
• Bicarbonate, forming carbonic acid
(H+ + HCO3- →H2CO)
• Ammonia, forming ammonium ions
(H+ + NH3 → NH4+)
• Hydrogen phosphate, forming dihydrogen phosphate
(H+ + HPO32- → H2PO3-)
Carbonic acid is converted to carbon dioxide (CO2) and water (H2O), and the CO2 is reabsorbed,
maintaining the buffering capacity of the blood. Hydrogen ions are excreted in the urine as ammonium salts
and hydrogen phosphate. The normal pH of urine varies from 4.5 to 8 depending on diet, time of day and
other factors. Individuals whose diet contains a large amount of animal proteins tend to produce more acidic
urine (lower pH) than vegetarians.
4. What are functions of kidney?

5. What is micturition? Describe the micturition reflex.

Answer: In infants, accumulation of urine in the bladder activates stretch receptors in the bladder wall
generating sensory (afferent) impulses that are transmitted to the spinal cord, where a spinal reflex is
initiated. This stimulates involuntary contraction of the detrusor muscle and relaxation of the internal
urethral sphincter, and expels urine from the bladder – this is micturition or voiding of urine.
When bladder control is established, the micturition reflex is still stimulated but sensory impulses also pass
upwards to the brain and there is awareness of the need to pass urine as the bladder fills (around 300–400
mL in adults). By learned and conscious effort, contraction of the external urethral sphincter and muscles
of the pelvic floor can inhibit micturition until it is convenient to pass urine.
Urination can be assisted by increasing the pressure within the pelvic cavity, achieved by lowering the
diaphragm and contracting the abdominal muscles. Over distension of the bladder is extremely painful, and
when this occurs there is a tendency for involuntary relaxation of the external sphincter to occur allowing
a small amount of urine to escape, provided there is no mechanical obstruction. Incontinence is the
involuntary loss of urine after bladder control has been established.
SHORT ANSWERS (2M)

1. Write significance of inulin clearance test
Answer: Inulin clearance, procedure by which the filtering capacity of the glomeruli is determined by
measuring the rate at which inulin, the test substance, is cleared from blood plasma. Inulin is the most
accurate substance to measure because it is a small, inert polysaccharide molecule that readily passes
through the glomeruli into the urine without being reabsorbed by the renal tubules.
2. What is renal clearance test? Mention its types.

Answer: The rate at which a particular chemical is removed from the plasma indicates kidney efficiency.
This rate of removal is called renal clearance. Tests of renal clearance can detect glomerular damage or
judge the progress of renal disease.
ELNAZ. Z 59
• Inulin clearance test
• Creatinine clearance test
• Para-aminohippuric acid (PAH) clearance
3.Define micturition
Answer: Micturition is the ejection of urine from the urinary bladder through the urethra to the outside of
the body.
CHAPTER 12. ENDOCRINE SYSTEM
LONG ESSAYS (10M)

1. Mention the hormones of pituitary gland and write the functions of each.
Answer:
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2. Write the synthesis, storage, release and functions of thyroid hormones.
Answer: Thyroid gland is composed of largely spherical follicles formed from cuboidal epithelium. These
secrete and store colloid, a thick sticky protein material. Between the follicles are other cells found singly
or in small groups: parafollicular cells, also called C-cells, which secrete the hormone calcitonin.
Thyroxine and tri-iodothyronine

Iodine is essential for the formation of the thyroid hormones, thyroxine (T4) and tri-iodothyronine (T3), so
numbered as these molecules contain four and three atoms of the element iodine respectively. The main
dietary sources of iodine are seafood, vegetables grown in iodine-rich soil and iodinated table salt. The
thyroid gland selectively takes up iodine from the blood, a process called iodine trapping.
Thyroid hormones are synthesised as large precursor molecules called thyroglobulin, the major constituent
of colloid. The release of T3 and T4 into the blood is stimulated by thyroid stimulating hormone (TSH)
from the anterior pituitary.
Secretion of TSH is stimulated by thyrotrophin releasing hormone (TRH) from the hypothalamus and
secretion of TRH is stimulated by exercise, stress, malnutrition, low plasma glucose levels and sleep. TSH
secretion depends on the plasma levels of T3 and T4 because it is these hormones that control the sensitivity
of the anterior pituitary to TRH. Through the negative feedback mechanism, increased levels of T3 and T4
decrease TSH secretion and vice versa. Dietary iodine deficiency greatly increases TSH secretion causing
proliferation of thyroid gland cells and enlargement of the gland. Secretion of T3 and T4 begins about the
third month of fetal life and increases at puberty and in women during the reproductive years, especially
during pregnancy.
Otherwise, it remains fairly constant throughout life. Of the two thyroid hormones, T4 is much more
abundant. However, it is less potent than T3, which is more physiologically important. Most T4 is converted
into T3 inside target cells.
Thyroid hormones enter the cell nucleus and regulate gene expression, i.e. they increase or decrease protein
synthesis. They enhance the effects of other hormones, e.g. adrenaline (epinephrine) and noradrenaline
(norepinephrine). T3 and T4 affect most cells of the body by:
• Increasing the basal metabolic rate and heat production
• Regulating metabolism of carbohydrates, proteins and fats.
T3 and T4 are essential for normal growth and development, especially of the skeleton and nervous system.
Most other organs and systems are also influenced by thyroid hormones. Physiological effects of T3 and
T4 on the heart, skeletal muscles, skin, digestive and reproductive systems are more evident when there is
underactivity or over activity of the thyroid gland and can be profound in childhood.
Calcitonin
This hormone is secreted by the parafollicular or C-cells in the thyroid gland. Calcitonin lowers raised
blood calcium (Ca2+) levels. It does this by acting on:
• Bone cells promoting their storage of calcium
• Kidney tubules inhibiting the reabsorption of calcium.
Its effect is opposite to that of parathyroid hormone, the hormone secreted by the parathyroid glands.
Release of calcitonin is stimulated by increased blood calcium levels. This hormone is important during
childhood when bones undergo considerable changes in size and shape.
3. Explain the physiological role of adrenal cortical hormones.

Answer: The adrenal cortex produces three groups of steroid hormones from cholesterol. They are
collectively called adrenocorticocoids (corticosteroids). The groups are:
• glucocorticoids
• mineralocorticoids
• sex hormones (androgens)
The hormones in each group have different characteristic actions but as they are structurally similar their
actions may overlap.
Glucocorticoids
Cortisol (hydrocortisone) is the main glucocorticoid but small amounts of corticosterone and cortisone are
also produced. Commonly these are collectively known as ‘steroids’; they are essential for life, regulating
metabolism and responses to stress. Secretion is controlled through a negative feedback system involving
the hypothalamus and anterior pituitary. It is stimulated by ACTH (adrenocorticotropic hormone) from the
anterior pituitary and by stress. Cortisol secretion shows marked circadian variation peaking between 4
ELNAZ. Z 61
a.m. and 8 a.m. and being lowest between midnight and 3 a.m. When the sleeping waking pattern is
changed, e.g. night shift working, it takes several days for ACTH/cortisol secretion to readjust.
Glucocorticoid secretion increases in response to stress, including infection and surgery. Glucocorticoids
have widespread metabolic effects generally concerned with catabolism (breakdown) of protein and fat that
makes glucose and other substances available for use. These include:
• Hyperglycaemia (raised blood glucose levels) caused by breakdown of glycogen and gluconeogenesis
(formation of new sugar from, for example, protein)
• Lipolysis (breakdown of triglycerides into fatty acids and glycerol for energy production) raising
circulating levels of free fatty acids
• Stimulating breakdown of protein, releasing amino acids, and increasing blood levels. Amino acids are
then used for synthesis of other proteins, e.g. enzymes, or for energy production
• Promoting absorption of sodium and water from renal tubules (a weak mineralocorticoid effect).
Mineralocorticoids (aldosterone)
Aldosterone is the main mineralocorticoid. It is involved in maintaining water and electrolyte balance.
Through a negative feedback system, it stimulates the reabsorption of sodium (Na+) by the renal tubules
and excretion of potassium (K+) in the urine. Sodium reabsorption is also accompanied by retention of
water and therefore aldosterone is involved in the regulation of blood volume and blood pressure too. Blood
potassium levels regulate aldosterone secretion by the adrenal cortex. When blood potassium levels rise,
more aldosterone is secreted. Low blood potassium has the opposite effect. Angiotensin also stimulates the
release of aldosterone. Renin–angiotensin–aldosterone system. When renal blood flow is reduced or
blood sodium levels fall, the enzyme renin is secreted by kidney cells. Renin converts the plasma protein
angiotensinogen, produced by the liver, to angiotensin 1. Angiotensin converting enzyme (ACE), formed
in small quantities in the lungs, proximal kidney tubules and other tissues, converts angiotensin 1 to
angiotensin 2, which stimulates secretion of aldosterone. Angiotensin 2 causes vasoconstriction and
increases blood pressure closing the negative feedback loop.
Sex hormones
Sex hormones secreted by the adrenal cortex are mainly androgens (male sex hormones) although the
amounts produced are insignificant compared with those secreted by the testes and ovaries in late puberty
and adulthood.
4. What are the hormones secreted by the pituitary gland? Discuss the regulation of their secretion
and physiological function.
5. Define hormone. Discuss various feedback mechanisms involved in the secretion of hormones.
Answer: Hormones are chemical messengers that are secreted directly into the blood, which carries them
to organs and tissues of the body to exert their functions.
1. Secretion of ACTH is also regulated by a negative feedback

mechanism, being suppressed when the blood level of ACTH rises
(Fig. 9.4). Other factors that stimulate secretion include
hypoglycaemia, exercise and other stressors, e.g. emotional states
and fever.
2. During childbirth increasing amounts of oxytocin are released
from the posterior pituitary into the bloodstream in response to
increasing stimulation of sensory stretch receptors in the uterine
cervix as the baby’s head progressively dilates it. Sensory impulses
are generated and travel to the control centre in the hypothalamus,
stimulating the posterior pituitary to release more oxytocin. In turn
this stimulates more forceful uterine contractions and greater
stretching of the uterine cervix as the baby’s head is forced further
downwards. This is an example of a positive feedback mechanism
which stops soon after the baby is delivered when distension of the
uterine cervix is greatly reduced (Fig. 9.5). The process of milk
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ejection also involves a positive feedback mechanism. Suckling
generates sensory impulses that are transmitted from the breast to
the hypothalamus. The impulses trigger release of oxytocin from
the posterior pituitary. On reaching the lactating breast, oxytocin
stimulates contraction of the milk ducts and myoepithelial cells
around the glandular cells, ejecting milk. Suckling also inhibits the
release of prolactin inhibiting hormone (PIH), prolonging
prolactin secretion and
lactation.
As osmotic pressure
rises, for example as a
result of dehydration,
secretion of ADH
increases. More water
is therefore reabsorbed
and the urine output is
reduced. This means
that the body retains
more water and the
rise in osmotic
pressure is reversed. Conversely, when the osmotic pressure of
the blood is low, for example after a large fluid intake, secretion
of ADH is reduced, less water is reabsorbed and more urine is
produced (Fig. 9.6). At high concentrations, for example after
severe blood loss, ADH causes smooth muscle contraction,
especially vasoconstriction in small arteries. This has a pressor effect, raising systemic blood pressure; the
alternative name of this hormone, vasopressin, reflects this effect.
SHORT ESSAYS (5M)

1. Write the functions of insulin and glucagon.
Answer: Insulin- Its main function is to lower raised blood nutrient levels, not only glucose but also amino
acids and fatty acids. These effects are described as anabolic, i.e. they promote storage of nutrients. When
nutrients, especially glucose, are in excess of immediate needs insulin promotes their storage by:
• Acting on cell membranes and stimulating uptake and use of glucose by muscle and connective tissue
cells
• Increasing conversion of glucose to glycogen (glycogenesis), especially in the liver and skeletal muscles
• Accelerating uptake of amino acids by cells, and the synthesis of protein
• Promoting synthesis of fatty acids and storage of fat in adipose tissue (lipogenesis)
• Decreasing glycogenolysis (breakdown of glycogen into glucose)
• Preventing the breakdown of protein and fat, and gluconeogenesis (formation of new sugar from, e.g.,
protein).
Secretion of insulin is stimulated by increased blood glucose levels, for example after eating a meal, and to
a lesser extent by parasympathetic stimulation, raised blood amino acid and fatty acid levels, and
gastrointestinal hormones, e.g. gastrin, secretin and cholecystokinin. Secretion is decreased by sympathetic
stimulation, glucagon, adrenaline, cortisol and somatostatin (GHRIH), which is secreted by the
hypothalamus and pancreatic islets.
Glucagon
Glucagon increases blood glucose levels by stimulating:
• Conversion of glycogen to glucose in the liver and skeletal muscles (glycogenolysis)
• Gluconeogenesis.
Secretion of glucagon is stimulated by low blood glucose levels and exercise, and decreased by
somatostatin and insulin.
2. Write the functions of glucocorticoids.
ELNAZ. Z 63
Answer: 1. Protein breakdown. Glucocorticoids increase the rate of protein breakdown, mainly in muscle
fibers, and thus increase the liberation of amino acids into the bloodstream.
2. Glucose formation. Upon stimulation by glucocorticoids, liver cells may convert certain amino acids or
lactic acid to glucose, which neurons and other cells can use for ATP production. Such conversion of a
substance other than glycogen or another monosaccharide into glucose is called gluconeogenesis.
3. Lipolysis. Glucocorticoids stimulate the breakdown of triglycerides and release of fatty acids from
adipose tissue into the blood.
4. Resistance to stress. Glucocorticoids work in many ways to provide resistance to stress. The additional
glucose supplied by the liver cells provides tissues with a ready source of ATP to combat a range of stresses,
including exercise, fasting, fright, temperature extremes, high altitude, bleeding, infection, surgery, trauma,
and disease. Because glucocorticoids make blood vessels more sensitive to other hormones that cause
vasoconstriction, they raise blood pressure. This effect would be an advantage in cases of severe blood loss,
which causes blood pressure to drop.
5. Anti-inflammatory effects. Glucocorticoids inhibit white blood cells that participate in inflammatory
responses. Unfortunately, glucocorticoids also retard tissue repair, and as a result, they slow wound healing.
Although high doses can cause severe mental disturbances, glucocorticoids are very useful in the treatment
of chronic inflammatory disorders such as rheumatoid arthritis.
6. Depression of immune responses. High doses of glucocorticoids depress immune responses. For this
reason, glucocorticoids are prescribed for organ transplant recipients to retard tissue rejection by the
immune system.
3. Write a short note on parathyroid glands.

Answer: There are four small parathyroid glands, each weighing around 50 g, two embedded in the
posterior surface of each lobe of the thyroid gland. They are surrounded by fine connective tissue capsules
that contain spherical cells arranged in columns with sinusoids containing blood in between them.
Functions
These glands secrete parathyroid hormone (PTH, parathormone). Secretion is regulated by blood calcium
levels. When they fall, secretion of PTH is increased and vice versa. The main function of PTH is to increase
blood calcium levels. This is achieved by increasing the calcium absorption from the small intestine and
reabsorption from the renal tubules. If these sources provide inadequate supplies then PTH stimulates
osteoclasts (bone-destroying cells) and calcium is released from bones into the blood. Parathormone and
calcitonin from the thyroid gland act in a complementary manner to maintain blood calcium levels within
the normal range. This is needed for:
• Muscle contraction
• Transmission of nerve impulses
• Blood clotting
• Normal action of many enzymes.
4. Describe the anatomical location, histology and physiological role of the pancreas.
Answer: The pancreas is a pale grey gland weighing about 60 grams. It is about 12–15 cm long and is
situated in the epigastric and left hypochondriac regions of the abdominal cavity. It consists of a broad
head, a body and a narrow tail. The head lies in the curve of the duodenum, the body behind the stomach
and the tail lies in front of the left kidney and just reaches the spleen. The abdominal aorta and the inferior
vena cava lie behind the gland. The pancreas is both an exocrine and endocrine gland.
Exocrine Function:
The pancreas contains exocrine glands that produce enzymes important to digestion. These enzymes
include trypsin and chymotrypsin to digest proteins; amylase for the digestion of carbohydrates; and lipase
to break down fats. When food enters the stomach, these pancreatic juices are released into a system of
ducts that culminate in the main pancreatic duct. The pancreatic duct joins the common bile duct to form
the ampulla of Vater which is located at the first portion of the small intestine, called the duodenum. The
common bile duct originates in the liver and the gallbladder and produces another important digestive
juice called bile. The pancreatic juices and bile that are released into the duodenum, help the body to digest
fats, carbohydrates, and proteins.
Endocrine Function:
The endocrine component of the pancreas consists of islet cells (islets of Langerhans) that create and release
important hormones directly into the bloodstream. Two of the main pancreatic hormones are insulin,
ELNAZ. Z 64
which acts to lower blood sugar, and glucagon, which acts to raise blood sugar. Maintaining proper blood
sugar levels is crucial to the functioning of key organs including the brain, liver, and kidneys.
5.Mention the hormones of anterior pituitary and explain their functions.

6. Discuss the functions of thyroxin.

Answer: Thyroxine is one of two hormones that together form what's referred to collectively as the thyroid
hormone. Thyroxine travels through the blood to the target cells and is then converted to triiodothyronine,
shortened to T3; think of T4 as the messenger, and T3 as the worker that carries out the order. T3 is the
active form of thyroid hormone and is primarily responsible for your metabolism, which is the process by
which your cells break down food and other substances into smaller molecules they can use.
Thyroid hormone works by entering a target cell's nucleus, binding to receptors, and starting transcription,
or the copying of DNA, for making proteins. The target genes are the ones involved in the metabolism of
glucose in your body. Thyroid hormone increases your metabolism and body heat production. In addition,
the thyroid hormones also regulates blood pressure, the development of skeletal and nervous tissues, and it
affects reproductive function.
7. Write the functions of hormones of neurohypophysis.

Answer: Refer Question No.1 (10 M) neurohypophysis also called as posterior pituitary.
SHORT ANSWERS (2M)

1. Write physiological functions of vasopressin.
Answer: Vasopressin regulates the body's water retention. It is released from the brain when the body is
dehydrated and causes the kidneys to conserve water, thus concentrating the urine and reducing urine
volume. At high concentrations, it also raises blood pressure by inducing moderate vasoconstriction.
Increasing the water permeability of distal convoluted tubule and collecting duct cells in the kidney, thus
allowing water reabsorption and excretion of more concentrated urine, i.e., antidiuresis.
2. Write symptoms of Addison’s disease.

Answer:
• Extreme fatigue
• Weight loss and decreased appetite
• Darkening of your skin (hyperpigmentation)
• Low blood pressure, even fainting
• Salt craving
• Low blood sugar (hypoglycemia)
• Nausea, diarrhea or vomiting
• Abdominal pain
• Muscle or joint pains
• Irritability
• Depression
• Body hair loss or sexual dysfunction in women
3. Write outcome of hyperthyroidism.

Answer: This syndrome, also known as thyrotoxicosis, arises as the body tissues are exposed to excessive
levels of T3 and T4. The main causes are:
• Graves’ disease
• Toxic nodular goitre
• Adenoma
4. What is cretinism?
Answer: Cretinism is a condition of severely stunted physical and mental growth owing to
untreated congenital deficiency of thyroid hormone (congenital hypothyroidism) usually owing to
maternal hypothyroidism.
ELNAZ. Z 65
5. State functions of hormones of adrenal medulla.
Answer: Adrenaline (epinephrine) and noradrenaline (norepinephrine) Together they potentiate the
fight or flight response by:
• Increasing heart rate
• Increasing blood pressure
• Diverting blood to essential organs, including the heart, brain and skeletal muscles, by dilating their
blood vessels and constricting those of less essential organs, such as the skin
• Increasing metabolic rate
• Dilating the pupils.
6. Define thyrotoxicosis and cretinism.

Answer: The term thyrotoxicosis refers to the hypermetabolic clinical syndrome resulting from serum
elevations in thyroid hormone levels, specifically free thyroxine (T4) and/or triiodothyronine (T3).
Cretinism is a condition of severely stunted physical and mental growth owing to
untreated congenital deficiency of thyroid hormone (congenital hypothyroidism) usually owing to
maternal hypothyroidism.
7. What is a pheochromocytoma and myxoedema.

Answer: A pheochromocytoma is a neuroendocrine tumor of the medulla of the adrenal glands or extra-
adrenal chromaffin tissue that failed to involute after birth, that secretes high amounts of catecholamines,
mostly norepinephrine, plus epinephrine to a lesser extent. Myxedema is a term used synonymously with
severe hypothyroidism. Hypothyroidism, also called underactive thyroid or low thyroid, is a
common disorder of the endocrine system in which the thyroid gland does not produce enough thyroid
hormone.
8. What is goitre.
Answer: A goitre is a swelling of the neck or larynx resulting from enlargement of the thyroid
gland (thyromegaly), associated with a thyroid gland that is not functioning properly.
9. Functions of ADH and oxytocin.

Answer: ADH - Conserves body water by decreasing urine volume; decreases water loss through
perspiration; raises blood pressure by constricting arterioles.
Oxytocin - Stimulates contraction of smooth muscle cells of the uterus during childbirth; stimulates
contraction of myoepithelial cells in the mammary glands to cause milk ejection.
10. Define acromegaly and gigantism.

Answer: Acromegaly is a disorder that results from excess growth hormone (GH) after the growth
plates have closed. The initial symptom is typically enlargement of the hands and feet. Gigantism, is a
condition characterized by excessive growth and height significantly above average. This condition is
caused by over-production of growth hormone.
11. Define diabetes mellitus and diabetes insipidus.

Answer: Diabetes mellitus (DM), commonly referred to as diabetes, is a group of metabolic diseases in
which there are high blood sugar levels over a prolonged period. Diabetes insipidus (DI) is
a condition characterized by excessive thirst and excretion of large amounts of severely dilute urine, with
reduction of fluid intake having no effect on the concentration of the urine.
12. What is positive feedback mechanism?

Answer: In a positive feedback system, the output enhances the original stimulus. A good example of a
positive feedback system is child birth. During labor, a hormone called oxytocin is released that intensifies
and speeds up contractions. The increase in contractions causes more oxytocin to be released and the cycle
goes on until the baby is born. The birth ends the release of oxytocin and ends the positive feedback
mechanism.
ELNAZ. Z 66
CHAPTER 13. REPRODUCTIVE SYSTEM
LONG ESSAYS (10M)

1. Describe the different phases of female reproductive cycle
Answer: The average length of the cycle is about 28 days. By
convention the days of the cycle are numbered from the
beginning of the menstrual phase, which usually lasts about 4
days. This is followed by the proliferative phase (approximately
10 days), then by the secretory phase (about 14 days).
Menstrual phase
When the ovum is not fertilised, the corpus luteum starts to
degenerate. (In the event of pregnancy, the corpus luteum is
supported by human chorionic gonadotrophin [hCG] secreted
by the developing embryo.) Progesterone and oestrogen levels
therefore fall, and the functional layer of the endometrium,
which is dependent on high levels of these ovarian hormones, is
shed in menstruation (Fig. 18.10C). The menstrual flow consists
of the secretions from endometrial glands, endometrial cells,
blood
from the degenerating capillaries and the unfertilised ovum.
During the menstrual phase, levels of oestrogen and
progesterone are very low because the corpus luteum that had
been active during the second half of the previous cycle has
degenerated. This means the hypothalamus and anterior
pituitary can resume their cyclical activity, and levels of FSH
begin to rise, initiating a new cycle.
Proliferative phase
At this stage an ovarian follicle, stimulated by FSH, is growing
towards maturity and is producing oestrogen, which stimulates
proliferation of the functional layer of the endometrium in
preparation for the reception of a fertilised ovum. The
endometrium thickens, becoming very vascular and rich in
mucus-secreting glands. Rising levels of oestrogen are
responsible for triggering a surge of LH approximately mid-
cycle. This LH surge triggers ovulation, marking the end of the
proliferative phase.
Secretory phase
After ovulation, LH from the anterior pituitary stimulates development of the corpus luteum from the
ruptured follicle, which produces progesterone, some oestrogen, and inhibin. Under the influence of
progesterone, the endometrium becomes oedematous and the secretory glands produce increased amounts
of watery mucus. This assists the passage of the spermatozoa through the uterus to the uterine tubes where
the ovum is usually fertilised. There is a similar increase in secretion of watery mucus by the glands of the
uterine tubes and by cervical glands that lubricate the vagina. The ovum may survive in a fertilisable form
for a very short time after ovulation, probably as little as 8 hours. The spermatozoa, deposited in the vagina
during intercourse, may be capable of fertilising the ovum for only about 24 hours although they can survive
for several days. This means that the period in each cycle during which fertilisation can occur is relatively
short. Observable changes in the woman’s body occur around the time of ovulation. Cervical mucus,
normally thick and dry, becomes thin, elastic and watery, and body temperature rises by about 1°C
immediately following ovulation. Some women experience abdominal discomfort in the middle of the
cycle, thought to correspond to rupture of the follicle and release of its contents into the abdominal cavity.
After ovulation, the combination of progesterone, oestrogen and inhibin from the corpus luteum suppresses
the hypothalamus and anterior pituitary, so FSH and LH levels fall. Low FSH levels in the second half of
the cycle prevent further follicular development in case a pregnancy results from the current cycle. If the
ovum is not fertilised, falling LH levels leads to degeneration and death of the corpus luteum, which is
dependent on LH for survival. The resultant steady decline in circulating oestrogen, progesterone and
ELNAZ. Z 67
inhibin leads to degeneration of the uterine lining and menstruation, with the initiation of a new cycle. If
the ovum is fertilised there is no breakdown of the endometrium and no menstruation. The fertilised ovum
(zygote) travels through the uterine tube to the uterus where it becomes embedded in the wall and produces
human chorionic gonadotrophin (hCG), which is similar to anterior pituitary luteinising hormone. This
hormone keeps the corpus luteum intact, enabling it to continue secreting progesterone and oestrogen for
the first 3–4 months of the pregnancy, inhibiting the maturation of further ovarian follicles. During that
time the placenta develops and produces oestrogen, progesterone and gonadotrophins.
2. Explain the steps involved in the process of spermatogenesis and oogenesis.

Answer: Spermatogenesis
In humans, spermatogenesis takes 65–75 days. It begins with
the spermatogonia, which contain the diploid (2n) number of
chromosomes (Figure 28.5). Spermatogonia are types of stem
cells; when they undergo mitosis, some spermatogonia
remain near the basement membrane of the seminiferous
tubule in an undifferentiated state to serve as a reservoir of
cells for future cell division and subsequent sperm
production. The rest of the spermatogonia lose contact with
the basement membrane, squeeze through the tight junctions
of the blood–testis barrier, undergo developmental changes,
and differentiate into primary spermatocytes. Primary
spermatocytes, like spermatogonia, are diploid (2n); that is,
they have 46 chromosomes.
Shortly after it forms, each primary spermatocyte replicates
its DNA and then meiosis begins (Figure 28.5). In meiosis I,
homologous pairs of chromosomes line up at the metaphase
plate, and crossing-over occurs. Then, the meiotic spindle
pulls one (duplicated) chromosome of each pair to an opposite
pole of the dividing cell. The two cells formed by meiosis I
are called secondary spermatocytes. Each secondary
spermatocyte has 23 chromosomes, the haploid number (n).
Each chromosome within a secondary spermatocyte,
however, is made up of two chromatids (two copies of the
DNA) still attached by a centromere. No replication of DNA
occurs in the secondary spermatocytes. In meiosis II, the
chromosomes line up in single file along the metaphase
plate, and the two chromatids of each chromosome separate.
The four haploid cells resulting from meiosis II are called
spermatids. A single primary spermatocyte therefore
produces four spermatids via two rounds of cell division
(meiosis I and meiosis II).
The final stage of spermatogenesis, spermiogenesis, is the
development of haploid spermatids into sperm. No cell
division occurs in spermiogenesis; each spermatid becomes
a single sperm cell. During this process, spherical
spermatids transform into elongated, slender sperm. An
acrosome (described shortly) forms atop the nucleus, which
condenses and elongates, a flagellum develops, and
mitochondria multiply. Sertoli cells dispose of the excess
cytoplasm that sloughs off. Finally, sperm are released from
their connections to Sertoli cells, an event known as
spermiation. Sperm then enter the lumen of the
seminiferous tubule. Fluid secreted by Sertoli cells pushes
sperm along their way, toward the ducts of the testes. At this
point, sperm are not yet able to swim.
Oogenesis Refer the Figure 28.15
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SHORT ESSAYS (5M)
1. Explain spermatogenesis
Answer: Refer question no. 2 (10M)
2. Describe the mechanism of action of hormonal contraceptives

Answer: Oral contraceptives (the pill) contain hormones designed to prevent pregnancy. Some, called
combined oral contraceptives (COCs), contain both progestin (hormone with actions similar to
progesterone) and estrogens. The primary action of COCs is to inhibit ovulation by suppressing the
gonadotropins of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The low levels of
FSH and LH usually prevent the development of a dominant follicle in the ovary. As a result, levels of
estrogens do not rise, the midcycle LH surge does not occur, and ovulation does not take place. Even if
ovulation does occur, as it does in some cases, COCs may also block implantation in the uterus and inhibit
the transport of ova and sperm in the uterine tubes. Progestins thicken cervical mucus and make it more
difficult for sperm to enter the uterus. Progestin-only pills thicken cervical mucus and may block
implantation in the uterus, but they do not consistently inhibit ovulation.
3. Describe the functions of ovary

Answer: Gamete production - The ovaries are the site of production and periodical release of egg cells,
the female gametes. In the ovaries, the developing egg cell (or oocyte) grows within the environment
provided by follicles. Follicles are composed of different types and number of cells according to the stage
of their maturation, and their size is indicative of the stage of oocyte development.
Endocrine function
Ovaries secrete estrogen, testosterone and progesterone. In women, fifty percent of testosterone is
produced by the ovaries and adrenal glands and released directly into the blood stream. Estrogen is
responsible for the appearance of secondary sex characteristics for females at puberty and for the
maturation and maintenance of the reproductive organs in their mature functional state. Progesterone
prepares the uterus for pregnancy, and the mammary glands for lactation. Progesterone functions with
estrogen by promoting menstrual cycle changes in the endometrium.
Ovarian aging
As women age, they experience a decline in reproductive performance leading to menopause. This decline
is tied to a decline in the number of ovarian follicles. The decline in ovarian reserve appears to occur at a
constantly increasing rate with age, and leads to nearly complete exhaustion of the reserve by about age 52.
As ovarian reserve and fertility decline with age, there is also a parallel increase in pregnancy failure and
meiotic errors resulting in chromosomally abnormal conceptions.
4. Write a note on IUD.

Answer: An intrauterine device (IUD) is a small object made of plastic, copper, or stainless steel that is
inserted by a health-care professional into the cavity of the uterus. IUDs prevent fertilization from taking
place by blocking sperm from entering the uterine tubes. The IUD most commonly used in the United States
today is the Copper T 380A, which is approved for up to 10 years of use and has long-term effectiveness
comparable to that of tubal ligation. Some women cannot use IUDs because of expulsion, bleeding, or
discomfort.
5. Write a short note on oral contraceptives

Answer: Mechanism of action refer question no. 2 (5M)
Combined pill. Contains both progestin and estrogens and is typically taken once a day for three weeks to
prevent pregnancy and regulate the menstrual cycle. The pills taken during the fourth week are inactive (do
not contain hormones) and permit menstruation to occur.
Seasonale. Contains both progestin and estrogens and is taken once a day in 3-month cycles of 12 weeks
of hormonecontaining pills followed by one week of inactive pills. Menstruation occurs during the
thirteenth week.
Minipill. Contains progestin only and is taken every day of the month.
6. Write a note on menstrual cycle

Answer: Refer question No. 1 (10 M)
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7. Classify temporary methods of contraception for females.
Answer:
1.Barrier methods use a physical barrier and are designed to prevent sperm from gaining access to the
uterine cavity and uterine tubes. A male condom is a nonporous, latex covering placed over the penis that
prevents deposition of sperm in the female reproductive tract. A vaginal pouch, sometimes called a female
condom, is designed to prevent sperm from entering the uterus. It is made of two flexible rings connected
by a polyurethane sheath. One ring lies inside the sheath and is inserted to fit over the cervix; the other ring
remains outside the vagina and covers the female external genitals. A diaphragm is a rubber, dome-shaped
structure that fits over the cervix and is used in conjunction with a spermicide. It can be inserted by the
female up to 6 hours before intercourse. A cervical cap resembles a diaphragm but is smaller and more
rigid. It fits snugly over the cervix and must be fitted by a health-care professional. Spermicides should be
used with the cervical cap.
2. An intrauterine device (IUD) is a small object made of plastic, copper, or stainless steel that is inserted
by a health-care professional into the cavity of the uterus. IUDs prevent fertilization from taking place by
blocking sperm from entering the uterine tubes. The IUD most commonly used in the United States today
is the Copper T 380A, which is approved for up to 10 years of use and has long-term effectiveness
comparable to that of tubal ligation. Some women cannot use IUDs because of expulsion, bleeding, or
discomfort.
3.Hormonal methods- Refer question no.5(5M)
4.Miscellaneous/ natural methods- Rhythm method. It involves abstaining from sexual activity on the
days that ovulation is likely to occur in each reproductive cycle. During this time (3 days before ovulation,
the day of ovulation, and 3 days after ovulation) the couple abstains from intercourse.
8. Describe the structure of ovary and testes.

Answer: Ovary - The ovaries have two layers of tissue. Medulla-This lies in the centre and consists of
fibrous tissue, blood vessels and nerves. Cortex-This surrounds the medulla. It has a framework of
connective tissue, or stroma, covered by germinal epithelium. It contains ovarian follicles in various stages
of maturity, each of which contains an ovum. Before puberty the ovaries are inactive but the stroma already
contains immature (primordial) follicles, which the female has from birth. During the childbearing years,
about every 28 days, one or more ovarian follicle (Graafian follicle) matures, ruptures and releases its ovum
into the peritoneal cavity. This is called ovulation and it occurs during most menstrual cycles. Following
ovulation, the ruptured follicle develops into the corpus luteum (meaning ‘yellow body’), which in turn
will leave a small permanent scar of fibrous tissue called the corpus albicans (meaning ‘white body’) on
the surface of the ovary.
Testes - In each testis are 200–300 lobules, and within each lobule are 1–4 convoluted loops of germinal
epithelial cells, called seminiferous tubules. Between the tubules are groups of interstitial cells (of Leydig)
that secrete the hormone testosterone after puberty. At the upper pole of the testis the tubules combine to
form a single tubule. This tubule, about 6 m in its full length,
is repeatedly folded and tightly packed into a mass called the
epididymis. It leaves the scrotum as the deferent duct (vas
deferens) in the spermatic cord. Blood and lymph vessels pass
to the testes in the spermatic cords.
9. Write a note on the role of sex hormones in the regulation

of menstrual cycle.
Answer: The hypothalamus secretes luteinising hormone
releasing hormone (LHRH), which stimulates the anterior
pituitary to secrete:
• Follicle stimulating hormone (FSH), which promotes the
maturation of ovarian follicles and the secretion of oestrogen,
leading to ovulation. FSH is therefore predominantly active in
the first half of the cycle. Its secretion is suppressed once
ovulation has taken place, to prevent other follicles maturing
during the current cycle.
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• Luteinising hormone (LH), which triggers ovulation, stimulates the development of the corpus luteum
and the secretion of progesterone. The hypothalamus responds to changes in the blood levels of oestrogen
and progesterone. It is stimulated by high levels of oestrogen alone (as happens in the first half of the cycle)
but suppressed by oestrogen and progesterone together (as happens in the second half of the cycle).
The average length of the cycle is about 28 days. By convention the days of the cycle are numbered from
the beginning of the menstrual phase, which usually lasts about 4 days. This is followed by the proliferative
phase (approximately 10 days), then by the secretory phase (about 14 days).
10. Write a note on female contraceptive devices.

Answer: An intrauterine device (IUD) is a small object made of plastic, copper, or stainless steel that is inserted by a
health-care professional into the cavity of the uterus. IUDs prevent fertilization from taking place by blocking sperm from
entering the uterine tubes. The IUD most commonly used in the United States today is the Copper T 380A®, which is
approved for up to 10 years of use and has long-term effectiveness comparable to that of tubal ligation. Some women
cannot use IUDs because of expulsion, bleeding, or discomfort.
11. Describe the internal structure and functions of testis.

Answer: Testes - In each testis are 200–300 lobules, and within each lobule are 1–4 convoluted loops of
germinal epithelial cells, called seminiferous tubules. Between the tubules are groups of interstitial cells
(of Leydig) that secrete the hormone testosterone after puberty. At the upper pole of the testis the tubules
combine to form a single tubule. This tubule, about 6 m in its full length, is repeatedly folded and tightly
packed into a mass called the epididymis. It leaves the scrotum as the deferent duct (vas deferens) in the
spermatic cord. Blood and lymph vessels pass to the testes in the spermatic cords.
Functions
Spermatozoa (sperm) are produced in the seminiferous tubules of the testes, and mature as they pass through
the long and convoluted epididymis, where they are stored. FSH from the anterior pituitary stimulates sperm
production. A mature sperm has a head, a body, and a long whip-like tail used for motility. The head is
almost completely filled by the nucleus, containing its DNA. It also contains the enzymes required to
penetrate the outer layers of the ovum to reach, and fuse with, its nucleus. The body of the sperm is packed
with mitochondria, to fuel the propelling action of the tail that powers the sperm along the female
reproductive tract. Successful spermatogenesis takes place at a temperature about 3°C below normal body
temperature. The testes are cooled by their position outside the abdominal cavity, and the thin outer
covering of the scrotum has very little insulating fat.
12.Write a note on sex determination (genetic basis).

Answer: Sexual differentiation in humans is the process of development of sex differences in humans.
It is defined as the development of phenotypic structures consequent to the action of hormones produced
following gonadal determination. Sexual differentiation includes development of different genitalia and the
internal genital tracts, breasts, body hair, and plays a role in gender identification.
The development of sexual differences begins with the XY sex-determination system that is present in
humans, and complex mechanisms are responsible for the development of the phenotypic differences
between male and female humans from an undifferentiated zygote. Females have two X chromosomes,
and males have a Y chromosome and an X chromosome. At an early stage in embryonic development, both
sexes possess equivalent internal structures.
A baby’s genetic sex is determined at the time of conception. When the baby is conceived,
a chromosome from the sperm cell, either X or Y, fuses with the X chromosome in the egg cell, determining
whether the baby will be genetically female (XX) or male (XY). To be genetically female, one needs to be
(XX), whereas to be a genetic male, (XY) is needed. It is the Y chromosome that is essential for the
development of the male reproductive organs, and with no Y chromosome, an embryo will develop into a
female. This is because of the presence of the sex determining region of the Y chromosome, also known as
the SRY gene.
SHORT ANSWERS (2M)

1. Explain corpus luteum
Answer: The corpus luteum is a temporary endocrine structure in female ovaries that is involved in the
production of relatively high levels of progesterone, moderate levels of estradiol and inhibin A. It is the
remains of the ovarian follicle that has released a mature ovum during a previous ovulation.
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2. Name Gonadotrophins and give their functions.
Answer: Gonadotropins are glycoprotein polypeptide hormones secreted by gonadotrope cells of
the anterior pituitary of vertebrates. Hormones are, Follicle stimulating hormone (FSH), which promotes
the maturation of ovarian follicles and the secretion of oestrogen, leading to ovulation. Luteinising hormone
(LH), which triggers ovulation, stimulates the development of the corpus luteum and the secretion of
progesterone and human chorionic gonadotropin (hCG) and equine chorionic gonadotropin (eCG).
3. Write surgical methods of family planning.

Answer: VASECTOMY-It is a procedure to cut and tie the tubes (vas deferens) that carry the sperm up
from the testicles.
TUBECTOMY-It is a procedure to close both fallopian tubes in a woman. This means that sperm can’t
get to the egg to fertilise it.
4. Name few contraceptive methods.

Answer: Refer question no.7 (5M)
5. Define menstrual cycle.

Answer: The uterine (menstrual) cycle is a concurrent series of changes in the endometrium of the uterus
to prepare it for the arrival of a fertilized ovum that will develop there until birth. If fertilization does not
occur, ovarian hormones wane, which causes the stratum functionalis of the endometrium to slough off.
6. What is a vasectomy and tubectomy?

7. Name the ducts of male reproductive system in order (proximal to distal).

Answer: Ampulla of ductus (vas) deferens →Ejaculatory duct →Ductus (vas) deferens
8. What are sex hormones?

Answer: A steroid hormone (as estradiol, progesterone, androstenedione, or testosterone) that is produced
especially by the ovaries, testes, or adrenal cortex and that exerts estrogenic, progestational, or androgenic
activity on the growth or function of the reproductive organs or on the development of secondary sex
characteristics.
9. Define the reproduction and list the organs of male reproductive system.
Answer: Sexual reproduction is the process by which organisms produce offspring by making germ cells called
Gametes. Scrotum, Testes, Epididymis, Spermatic Cords and Ductus Deferens, Seminal Vesicles,
Ejaculatory Duct, Urethra, Prostate, Cowper’s Glands and Penis,
10. list the organs of male reproductive system.

11. What is parturition?

Answer: Labor is the process by which the fetus is expelled from the uterus through the vagina, also
referred to as giving birth. A synonym for labor is parturition.
12. Define the terms- menarche and menopause.

Answer: In females, the reproductive cycle normally occurs once each month from menarche, the first
menses, to menopause, the permanent cessation of menses.
CHAPTER 14 SENSE ORGANS
LONG ESSAYS (10M)

1. Write a neat, labelled diagram of eye and explain the physiology of vision.
Answer: Physiology of vision-Refraction of light rays is the deflection or bending of a ray as it passes
through one object and into another of greater or lesser density. The refraction of light within the eye takes
place in the following pathway of structures:
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• Cornea
• Aqueous humor
• Lens
• Vitreous humor
The lens is the only adjustable
part of the refraction system.
When looking at distant
objects, the ciliary muscle is
relaxed and the lens in
elongated and thin.
When looking at near objects,
the ciliary muscle contracts to
form a smaller circle. The
elastic lens recoils and bulges
in the middle, having a
greater refractive power. When light rays strike the retina, they stimulate chemical reactions in the rods and
cones. In rods, the chemical rhodopsin breaks down to form scotopsin and retinal. This chemical reaction
generates an electrical impulse. Rhodopsin is then resynthesized in a slower reaction.
In cones, the chemical reactions are brought about by different wavelengths of light. It is believed there are
three types of cones:
• Red-absorbing
• Blue-absorbing
• Green-absorbing
Each type absorbs wavelengths over about one-third of the visible light spectrum, causing red cones, for
example, to absorb light from the red, orange, and yellow wavelengths. The chemical reactions in cones
also generate electrical impulses. Impulses from the rods and cones are transmitted to ganglion neurons,
which converge at the optic disc to become the optic nerve, passing posteriorly through the wall of the
eyeball. The optic nerves from both eyes converge at the optic chiasma, which is just in front of the
pituitary gland. Here, the medial fibers of each optic nerve cross to the other side. Crossing permits each
visual area to receive impulses from both eyes, important for binocular vision.
Visual areas are located in the occipital lobes of the cerebral cortex of the brain. Although each eye
transmits a slightly different picture, the visual areas put them together or integrate them to make a single
image. This is called binocular vision. Visual areas also right the image since it appears on the retina
upside down. The image on film in a camera is also upside down, but this is not apparent because, when
they are viewed, they appear right side up, an accomplishment of the brain.
2. Write a neat, labelled diagram of ear and explain the physiology of hearing.
Answer: Physiology of hearing
The auricle, because of its shape,
collects and concentrates the waves
and directs them along the auditory
canal causing the tympanic membrane
to vibrate. Tympanic membrane
vibrations are transmitted and
amplified through the middle ear by
movement of the ossicles (Fig. 8.6).
At their medial end the footplate of the
stapes rocks to and fro in the oval
window, setting up fluid waves in the
perilymph of the scala vestibuli. Some
of the force of these waves is
transmitted along the length of the
scala vestibule and scala tympani, but most of the pressure is transmitted into the cochlear duct. This causes
ELNAZ. Z 73
a corresponding wave motion in the
endolymph, resulting in vibration of the basilar
membrane and stimulation of the auditory
receptors in the hair cells of the spiral organ.
The nerve impulses generated pass to the brain
in the cochlear(auditory) portion of the
vestibulocochlear nerve. The fluid wave is
finally expended into the middle ear by
vibration of the membrane of the round
window. The vestibulocochlear nerve transmits
the impulses to the auditory nuclei in the
medulla, where they synapse before they are
conducted to the auditory area in the temporal
lobe of the cerebrum. Because some fibres cross
over in the medulla and others remain on the
same side, the left and right auditory areas of
the cerebrum receive impulses from both ears.
Sounds of different frequencies stimulate the
basilar membrane (Fig. 8.6A) at different places
along its length, allowing discrimination of
pitch. The volume depends on the magnitude of
the sound waves and is measured in decibels
(dB). The greater the amplitude of the wave
created in the endolymph, the greater is the
stimulation of the auditory receptors in the hair
cells in the spiral organ, enabling perception of
volume.
SHORT ESSAYS (5M)

1. Draw a neat-labelled diagram of skin.
Answer:
2. Describe the structure of eyeball
Answer: There are three layers of tissue in
the walls of the eye:
• The outer fibrous layer: sclera and cornea
• The middle vascular layer or uveal tract:
consisting of the choroid, ciliary body and
iris
• The inner nervous tissue layer: the retina.
Structures inside the eyeball include the
lens, aqueous fluid and vitreous body.
Diagram refer Question no.1 (10M)
3. Draw a neat-labeled diagram of ear.

What is the non-hearing function of ear?
Answer: Diagram refer Question no. 2
(10M)
Physiology of balance - The semicircular canals and the vestibule (utricle and saccule) are concerned with
balance, or equilibrium. The arrangement of the three semicircular canals, one in each plane, not only
allows perception of the position of the head in space but also the direction and rate of any movement. Any
change of position of the head causes movement in the perilymph and endolymph, which bends the hair
cells and stimulates the sensory receptors in the utricle, saccule and ampullae. The resultant nerve impulses
are transmitted by the vestibular nerve, which joins the cochlear nerve to form the vestibulocochlear nerve.
The vestibular branch passes first to the vestibular nucleus, then to the cerebellum. The cerebellum also
receives nerve impulses from the eyes and proprioceptors (sensory receptors) in the skeletal muscles and
joints. The cerebellum coordinates incoming impulses from the vestibular nerve, the eyes and
ELNAZ. Z 74
proprioceptors. Thereafter, impulses are transmitted to the cerebrum and skeletal muscles enabling
perception of body position and any adjustments needed to maintain posture and balance. This maintains
upright posture and fixing of the eyes on the same point, independently of head movements.
4. Describe the structure of olfactory receptors.

Answer: These are the sensory nerves of smell. They originate as chemoreceptors (specialised olfactory
nerve endings) in the mucous membrane of the roof of the nasal cavity above the superior nasal conchae.
On each side of the nasal septum nerve fibres pass through the cribriform plate of the ethmoid bone to the
olfactory bulb where interconnections and synapses occur. From the bulb, bundles of nerve fibres form the
olfactory tract, which passes backwards to the olfactory area in the temporal lobe of the cerebral cortex in
each hemisphere where the impulses are interpreted and odour perceived.
SHORT ANSWERS (2M)

1. What are the functions of skin?
Answer: 1. Regulates body temperature.
2. Stores blood.
3. Protects body from external environment.
4. Detects cutaneous sensations.
5. Excretes and absorbs substances.
6. Synthesizes vitamin D.
2. Functions of photoreceptors.
Answer: Photoreceptors are the cells in the retina that respond to light. Their distinguishing feature is the
presence of large amounts of tightly packed membrane that contains the photopigment rhodopsin or a
related molecule. The tight packing is needed to achieve a high photopigment density, which allows a large
proportion of the light photons that reach the photoreceptor to be absorbed. Photon absorption contributes
to the photoreceptor’s output signal.
3. Write the non-auditory functions of ear.

4. What are olfactory receptors?

5. What are gustatory receptors?

Answer: A gustatory receptor is a type of receptor which facilitates the sensation of taste. When food or
other substances enter the mouth, molecules interact with saliva and are bound to taste receptors in the oral
cavity and other locations. Molecules which give a sensation of taste are considered "sapid".
6. What is myopia and hypermetropia?

Answer: Near-sightedness, also known as short-sightedness and myopia, is a condition of the eye where
light focuses in front of, instead of on, the retina. This causes distant objects to be blurry while close objects
appear normal. Far-sightedness, also known as long-sightedness and hypermetropia, is a condition of
the eye in which light is focused behind, instead of on, the retina. This causes close objects to be blurry,
while far objects may appear normal.
7. What is glaucoma?
Answer: Glaucoma is a group of eye diseases which result in damage to the optic nerve and vision
loss. The most common type is open-angle glaucoma with less common types including closed-angle
glaucoma and normal-tension glaucoma.
8. Mention the ear ossicles and their location.

Answer: The malleus - This is the lateral hammer-shaped bone. The handle is in contact with the
tympanic membrane and the head forms a movable joint with the incus.
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The incus - This is the middle anvil-shaped bone. Its body articulates with the malleus, the long process
with the stapes, and it is stabilised by the short process, fixed by fibrous tissue to the posterior wall of the
tympanic cavity.
The stapes - This is the medial stirrup-shaped bone. Its head articulates with the incus and its footplate fits
into the oval window.
9. Mention the papillae and taste buds.

Answer: Taste buds are found in elevations on the tongue called papillae, which provide a rough texture to the upper
surface of the tongue. Three types of papillae contain taste buds they are: Vallate (circumvallate) papillae, Fungiform
papillae, Foliate papillae.
CHAPTER 15. SKELETAL MUSCLE
SHORT ESSAYS (5M)

1. Write about the physiology of skeletal muscle contraction. Write a note on neuromuscular
junction.
Answer: Theory of muscle contraction can be broken down into four distinct stages, these are;
a. Muscle activation: The motor nerve stimulates an action potential (impulse) to pass down
a neuron to the neuromuscular junction. This stimulates the sarcoplasmic reticulum to
release calcium into the muscle cell.
b. Muscle contraction: Calcium floods into the muscle cell binding with troponin allowing
actin and myosin to bind. The actin and myosin cross bridges bind and contract using ATP
as energy.
c. Recharging: ATP is re-synthesised (re-manufactured) allowing actin and myosin to
maintain their strong binding state.
d. Relaxation: Relaxation occurs when stimulation of the nerve stops. Calcium is then
pumped back into the sarcoplasmic reticulum breaking the link between actin and myosin.
Actin and myosin return to their unbound state causing the muscle to relax. Alternatively,
relaxation (failure) will also occur when ATP is no longer available.
In order for a skeletal muscle contraction to occur;

1. There must be a neural stimulus.
2. There must be calcium in the muscle cells.
3. ATP must be available for energy.
So, a few things can stop a contraction;

o Energy system fatigue: There is no more ATP left in the muscle cell so it can’t keep
contracting.
o Nervous system fatigue: The nervous system is not able to create impulses sufficiently or
quickly enough to maintain the stimulus and cause calcium to release.
o Voluntary nervous system control: The nerve that tells the muscle to contract stops
sending that signal because the brain tells it to, so no more calcium ions will enter the muscle
cell and the contraction stops.
o Sensory nervous system information: For example, a sensory neuron (nerves that detect
stimuli like pain or how heavy something is) provides feedback to the brain indicating that
a muscle is injured while you are trying to lift a heavy weight and consequently the impulse
to that muscle telling it to contract is stopped.
A neuromuscular junction is a chemical synapse formed by the contact between a motor neuron and
a muscle fiber. It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the
muscle fiber, causing muscle contraction.
Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy.
Synaptic transmission at the neuromuscular junction begins when an action potential reaches the
presynaptic terminal of a motor neuron, which activates voltage-dependent calcium channels to allow
calcium ions to enter the neuron. Calcium ions bind to sensor proteins on synaptic vesicles, triggering
vesicle fusion with the cell membrane and subsequent neurotransmitter release from the motor neuron into
ELNAZ. Z 76
the synaptic cleft. Motor neurons release acetylcholine (ACh), a small molecule neurotransmitter, which
diffuses across the synaptic cleft and binds to nicotinic acetylcholine receptors (nAChRs) on the cell
membrane of the muscle fiber, also known as the sarcolemma. nAChRs are ionotropic receptors, meaning
they serve as ligand-gated ion channels. The binding of ACh to the receptor can depolarize the muscle fiber,
causing a cascade that eventually results in muscle contraction.
2. Describe the structure of skeletal muscle.

Answer: Skeletal muscle fiber is a single cylindrical
muscle cell. An individual skeletal muscle may be made
up of hundreds, or even thousands, of muscle fibers
bundled together and wrapped in a connective tissue
covering. Each muscle is surrounded by a connective
tissue sheath called the epimysium. Fascia, connective
tissue outside the epimysium, surrounds and separates
the muscles. Portions of the epimysium project inward
to divide the muscle into compartments. Each
compartment contains a bundle of muscle fibers. Each
bundle of muscle fiber is called a fasciculus and is
surrounded by a layer of connective tissue called the
perimysium. Within the fasciculus, each individual
muscle cell, called a muscle fiber, is surrounded by
connective tissue called the endomysium.
Skeletal muscle cells (fibers), like other body cells, are soft and fragile. The connective tissue covering
furnish support and protection for the delicate cells and allow them to withstand the forces of contraction.
The coverings also provide pathways for the passage of blood vessels and nerves.
Commonly, the epimysium, perimysium, and endomysium extend beyond the fleshy part of the muscle, the
belly, to form a thick rope like tendon or a broad, flat sheet-like aponeurosis. The tendon and aponeurosis
form indirect attachments from muscles to the periosteum of bones or to the connective tissue of other
muscles. Typically, a muscle spans a joint and is attached to bones by tendons at both ends. One of the
bones remains relatively fixed or stable while the other end moves as a result of muscle contraction.
Skeletal muscles have an abundant supply of blood vessels and nerves. This is directly related to the primary
function of skeletal muscle, contraction. Before a skeletal muscle fiber can contract, it has to receive an
impulse from a nerve cell. Generally, an artery and at least one vein accompany each nerve that penetrates
the epimysium of a skeletal muscle. Branches of the nerve and blood vessels follow the connective tissue
components of the muscle of a nerve cell and with one or more minute blood vessels called capillaries.
SHORT ANSWERS (2M)

1. Write a short note on Myasthenia gravis.
Answer: Myasthenia gravis (MG) is a long-term neuromuscular disease that leads to varying degrees of
skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and
swallowing. It can result in double vision, drooping eyelids, trouble talking, and trouble walking.
2. How do isotonic and isometric contractions differ?

Answer: An isotonic contraction is one in which the muscle maintains the same tension as it shortens.
Examples of activities that involve isotonic contractions include walking, running or lifting a light object.
Isometric contractions of this variety, the muscle does not shorten and its tension never exceeds the
opposing force. Examples of isometric exercises include holding a weight in place above the ground or
pushing against a stationary object.
3. Mention the properties of skeletal muscle

Answer: Excitability: this refers to muscle tissue being able to react to nervous stimulation.
Extensibility: this refers to the ability of muscle tissue to lengthen when contracting and provide the effort
required to move the lever system (the bones and joints), producing coordinated movement.
Elasticity: this refers to the ability of muscle tissue to return to its normal resting length once it has been
stretched. A useful analogy is that of an elastic band, that will always resume its resting shape after it has
ELNAZ. Z 77
been stretched. This property enables the muscle to prepare for a series of repeated contractions, which is
normally required when performing exercise or sport.
Contractility: this refers to the capacity of a muscle to contract or shorten forcibly when stimulated by
nerves and hormones (excitability).
4. Draw neat labelled diagram of sarcomere

Answer:
5. Mention the proteins of skeletal muscle.

Answer:
• Actin
• Myosin
• Regulatory proteins
• Contractile proteins
• Structural proteins
• Tropomyosin
• Troponin
• Titin
• Nebulin
• Desmin
• Myomesin
• Alpha-actinin
• Dystrophin
6.Define the term Rigor- Mortis

Answer: It's the result of the body's loss of adenosine triphosphate (or ATP), which is a substance that
gives energy to the muscles. Rigor mortis is a valuable tool to any death investigation since it can narrow
down the timeframe of death. Another term for rigor mortis is postmortem rigidity.
CHAPTER 16. SPORTS PHYSIOLOGY
SHORT ANSWERS (2M)

1. Enlist the drugs used by athletes.
Answer:
• Anabolic steroids
• Androstenedione
• Human Growth Hormone (HGH)
• Erythropoietin
• Diuretics
• Creatine
• Stimulants
ELNAZ. Z 78
2. Write the effect of exercises on CVS.
Answer:
A. Decrease in resting heart rate. Because the rigors of regular exercise require so much work from the
cardiovascular system, sedentary periods become even easier for the heart by comparison. The heart
eventually becomes more efficient, and no longer needs to beat as quickly to supply the body with
blood while at rest.
B. Stroke volume increases at rest. Resting heart rate is able to slow down because the heart is now
trained to pump a larger quantity of blood with every beat.
C. Improved circulation. In response to the need to supply the muscles with more oxygen during
exercise, the body increases its number of capillaries, the smallest blood vessels in the body.
Existing capillaries also open wider.
D. Blood pressure decreases by up to 10 mmHg. An mmHg is a unit used for measuring pressure levels.
E. Blood volume increases. The body produces a greater number of red blood cells in order to keep
the muscles supplied with oxygen during heavy exercise.
3.Write the effects of exercise on respiration.

Answer: Breathing pattern
Over time, with consistent aerobic exercise, your resting respiration rate slows. This is a result of enhanced
respiratory muscle endurance and strength. With every breath, your air flow volume is improved compared
with the volume prior to an exercise program.
Air Exchange
Another result of high-intensity endurance training is a more efficient air exchange. Oxygen is readily
accepted into the lungs and bloodstream for transportation to the working muscles. Carbon dioxide is more
effectively eliminated due to the improved respiratory muscle function. When oxygen and carbon dioxide
exchanges are made at a high level, the body maintains equilibrium, which helps reduce stress and anxiety
and improves mental and physical health.
4.Effects of athletic training on muscles.

Answer: The relative ratio of fast glycolytic (FG) and slow oxidative (SO) fibers in each muscle is
genetically determined and helps account for individual differences in physical performance. The athletes
muscle fibers show slight increases in diameter, number of mitochondria, blood supply, and strength. By
contrast, exercises that require great strength for short periods produce an increase in the size and strength
of FG fibers. The increase in size is due to increased synthesis of thick and thin filaments.
5.Effects of exercise on body heat.

Answer: Your muscles quickly deplete stored energy when you start exercising. To make more energy,
muscles combine oxygen with ATP. This process creates heat energy as a byproduct. Extra heat raises your
body temperature, so your body needs to eliminate heat as quickly as possible. Temperature sensors tell the
hypothalamus your body temperature is increasing, and something needs to lower it. During exercise, extra
blood flows to your muscles to keep them going. When your body temperature starts to elevate, extra blood
flows to your skin, so evaporation, or sweat, can help cool you off. Blood flow diverted from other organs,
such as the kidney and liver, allows more blood to flow to your skin surface. Some of the extra heat picked
up in the circulatory system is eliminated by respiration as you breathe out heated air.
6.Effects of exercise on body fluid and salts.

Answer: Exercise increases the loss of water in two ways
1. It increase rate respiratory tract
2. Exercise increase the body heat and thus result in excessive sweating of respiration, which increase
water loss through the skin
ELNAZ. Z 79
When a person sweats, small amounts of electrolytes—the electrically charged minerals sodium, potassium,
chloride, and magnesium—are lost from the body along with water. Salt losses are greatest in beginners.
Training improves electrolyte retention
ELNAZ. Z 80

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CHAPTER 1. Scope of anatomy and physiology, basic terminologies used in this subject.

SHORT ESSAYS (2M)

1.Define Anatomy and Physiology?

2.Define anatomical position, sagittal plane?

3.Mention the descriptive terms used in Anatomy?

CHAPTER 2. STRUCTURE OF CELL-ITS COMPONENTS AND THEIR FUNCTIONS.

SHORT ESSAY (5M)

1.Explain the structure and functions of cell membrane.

2. Describe the functions of Golgi complex and mitochondria.

3. Mention different cell organelles with their functions.

5.Discuss the structure and functions of ribosomes and lysosomes.

SHORT ANSWERS (2M)

1. Write the functions of mitochondria.

2. Explain the functions of plasma membrane.

3. Why are mitochondria referred to as “power houses” of the cell?

6. Lysosomes and chromosomes

7. Mention the components of a cell.

CHAPTER 3. ELEMENTARY TISSUES OF THE HUMAN BODY

SHORT ESSAYS (5M)

1.Classify tissues with examples.

Classification of Connective Tissue:

2.Explain the differences among skeletal, smooth and cardiac muscles.

4.Differenciate between loose and dense connective tissues.

5.Describe the different types of epithelial tissues with examples.

6.Explain the structure and functions of neuron.

SHORT ANSWERS (2M)

2. Classify connective tissue with examples.

Classification of Connective Tissue:

3. Draw a neat labelled diagram of neuron.

4. Classify simple epithelium with examples.

6. Write the general characteristics of epithelial tissue.

CHAPTER 4. OSSEOUS SYSTEM

SHORT ESSAYS (5M)

1. Classify joints with examples

2. Explain the Haversian canal system of bone.

4. Describe angular and special movements of joints.

Angular movements (Increase or decrease in the angle between bones)

5. What is synovial joint? Explain its types with examples.

6.Classify axial skeletal system with examples.

Ethmoid (1) Mandible (1) Stapes (2) Lumbar vertebrae (5)

Sphenoid (1) Nasal (2) Sacrum (1)

7.Classify appendicular skeletal system with examples.

8.Classify bones on the basis of shape along with examples.

4. Irregular "Irregular bones" have complicated shapes • Atlas bone

SHORT ANSWERS (2M)

4. Write the histology of bone

5. Name the bones of cranium

6. Name the bone cells

8. Mention the bones of the upper limb.

9. Mention the bones of the lower limb.

10. Name the bones of the vertebral column.

11.Write the functions of bone.

CHAPTER 5. HAEMOPOIETIC SYSTEM

LONG ESSAYS (10Marks)

OTHER SOLUTES Inorganic salts. Positively charges ions(cations) include Na +,K+,Ca+,Mg2+;

FORMED ELEMENTS FUNCTIONS

3. Describe the process of Erythropoiesis and factors required or influencing erythropoiesis.

SHORT ESSAYS (5M)

3. Write any eight functions of blood.

5. Classify leucocytes. Mention its functions.