Module 3

Circulatory and
Respiratory
Systems
2007NSC Human Anatomy

Caitlin Healy
Weeks 5 and 6
Lecture 1 (a): Blood
Learning Outcomes
- Name the basic components of blood and define hematocrit.
- List some of the molecules in blood plasma.
- Describe the unique structural features and functions of erythrocytes.
- List the five classes of leukocytes, along with the structural characteristics of each.
- Describe the structure of platelets and their role in blood clotting.
- Distinguish red bone marrow from yellow bone marrow.
- Describe the basic histologic structures of red bone marrow.
- Define hematopoiesis and blood stem cell.
- Explain the differentiation of the various types of blood cells.
- Consider some common disorders of erythrocytes and leukocytes.
Composition of Blood
- Blood = cellular components (formed elements)
suspended in plasma
- ~8% of body mass
- Males: 5-6 litres
- Females: 4-5 litres

Plasma
- Normally ~55% of whole blood
- straw-coloured liquid = 91.5% water; 8.5% solutes.
- Plasma solutes:
o Ions (e.g. Na2+ and Cl- )
o Proteins (e.g. albumin, globulins and fibrinogen).
o Nutrients (sugars, amino acids and lipids)
o Waste products (e.g. urea and ammonia)
o Gases (e.g. O2 and CO2 )
o Hormones and vitamins
- Serum = plasma – clotting factors

Cellular Components of Blood

- Haematocrit: % of blood volume that is cellular (normally ~45%)
- Erythrocytes (red
blood cells);
leucocytes (white
blood cells); platelets
o All originate
in the bone
marrow

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Erythrocytes
- 4.3-5.2 (♀) and 5.1-5.8 (♂) x 106 erythrocytes/mm3 blood
- oxygen transport
- biconcave discs:
o flexible
o high surface area/vol.
- no nucleus or organelles
- 97% of non-water volume is haemoglobin
- lifespan of 100-120 days
- Exclusively reside in vascular system

Leucocytes
- Protect against infectious microorganisms
- 4800-11000 leucocytes/mm3 blood
- Can pass through capillary walls to enter tissues (diapedesis)

Relative frequency
- 4800-11000 leucocytes/μl blood (normal blood range)
- Never – Let – Monkeys – Eat – Bananas

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Platelets
- cellular fragments – derived from
megakaryocytes
- aka thrombocytes
- central to the initiation of clotting

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Haematopoiesis and the Bone Marrow
Haemato = blood

Poiesis = to make

Spongy bone is the site of red

bone marrow, which hosts
normal haematopoiesis

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Blood Cell Development

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Disorders of the Blood
- Anaemia: deficiency of RBCs (or haemoglobin)
- Sickle cell anaemia: haemoglobin crystallisation
- Polycythaemia: excess of RBCs (or haemoglobin)
- polycythaemia vera: tumour characterised by excessive erythropoiesis
- Leucocytosis: WBC count above the normal range in the blood

DISORDER: EXCESS OF: ASSOCIATED WITH:

NEUTROPHILIA Neutrophils Infections and inflammation
LYMPHOCYTOSIS Lymphocytes Viral infections and leukaemia
MONOCYTOSIS Monocytes Infections and leukaemia
EOSINOPHILIA Eosinophils Allergies and parasitic infections
BASOPHILIA Basophils Leukaemia

Lecture 1 (b): The Heart

Learning Outcomes
- Describe the orientation, location, and surface anatomy of the heart in the thorax.
- Describe the layers of the pericardium and the tissue layers of the heart wall.\
- List the important structural features of each heart chamber: right and left atria, and right and
left ventricles.
- Name the heart valves and describe their locations and functions. Indicate where on the chest
wall each of the valves is heard.
- Describe the cardiac skeleton and explain its functions.
- Describe the path of a drop of blood through the four chambers of the heart and the
systemic and pulmonary circuits.
- Describe the structure of cardiac muscle tissue.
- Describe the structure of intercalated discs and discuss their importance in the contraction of
cardiac muscle.
- Name the components of the conducting system of the heart and describe the conduction
pathway.
- Describe the locations of the coronary arteries and cardiac veins on the heart surface.
- Define cardiomyopathy and coronary artery disease.

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The Heart

Location of the Heart

- Lies within the thoracic cavity.
- The base lies posteriorly and
contains the major blood
vessels of the heart
- The apex of the heart lies on the
diaphragm and directs
anteriorly, inferiorly and to the
left (5th intercostal space 7-9cm
to the left of the midline)

Layers of Heart – Pericardium

- surrounded by triple-layered pericardium

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 - Fibrous pericardium - dense irregular connective tissue; fuses to major blood vessels
superiorly, diaphragm inferiorly, and sternum anteriorly
- Serous pericardium - loose connective tissue (2 layers); secretes serous pericardial fluid
- Parietal layer of serous pericardium attaches to the fibrous pericardium
- Visceral layer of the serous pericardium is bound to cardiac muscle
- Reduces friction

Layers of Heart
- Epicardium
o Visceral layer of the serous
pericardium blood vessels,
lymphatics and nerves
underneath
- Myocardium
o Multiple interlocking layers of
cardiac muscle tissue
(cardiomyocytes)
- Endocardium
o Internal surface
o Simple squamous epithelium, lines the chambers and valve

Chambers of Heart
- the atria are divided internally by the interatrial septum
- the ventricles are divided internally by the interventricular septum

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External Features of Heart
- The four chambers of the heart can be identified by sulci on the external surface
- Interatrial sulcus separates the left and right atria
- Coronary sulcus separates the atria and the ventricles (atrioventricular groove)
- Anterior interventricular sulcus separates the left and right ventricles on the anterior surface
- Posterior interventricular sulcus separates the left and right ventricles on the posterior
surface

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Right Atrium
- Receives deoxygenated blood via the superior
vena cava, inferior vena cava, and coronary sinus
- Consists of smooth posterior wall and pectinate
muscles on anterior wall (atrial
appendage/auricle) – divided by crista terminalis
- Contains the fossa ovalis (remnant of the foetal
foramen ovale)
- Blood passes through tricuspid valve (R
atrioventricular valve)

Right Ventricle
- Receives deoxygenated blood from the
right atrium
- Located anteriorly
- The tricuspid valve is connected to papillary
muscles via chordae tendineae
- Trabeculae carneae (ridges of
myocardium)
- Pulmonary valve leads to the pulmonary
trunk, then to the pulmonary arteries

Left Atrium
- Receives oxygenated blood from the lungs via the
right and left pulmonary veins (4)
- Located posteriorly, forms most of base
- Most of atrial wall is smooth (unlike RA) –
pectinate muscles in auricle only
- Separated from the R. atrium by atrial septum
- Blood passes through the bicuspid valve (left
atrioventricular valve/mitral valve)

Left Ventricle
- Has the thickest myocardium
- Located posteriorly
- The left AV valve has chordae tendineae
connecting to the cusps and papillary
muscles
- Oxygenated blood leaves the left ventricle
by passing through the aortic valve into the
ascending aorta

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 - Separated from RV by interventricular septum (muscular and membranous

Heart Valves
- aortic and pulmonary valves = semilunar valves
- cardiac skeleton – dense connective

AV valve function

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Semilunar Valve function

Structure of Heart Valves

- Heart valves consist of several microscopic layers:
o Atrialis (AV) or Ventricularis (SL) – elastic fibres, collagen and endothelium.
o Spongiosa – proteoglycans, elastic fibres
o Fibrosa – “load bearing” fibrillar collagen fibre core (mostly type III)

Heart Beats and Sounds

- Heartbeat: single sequence of atrial and then ventricular contraction ‘Lub Dub’
- Lub = closing of AV valves at the start of ventricular contraction;
- Dub = closing of SL valves at the end of ventricular contraction.

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 Systole= ventricular/atrial contraction;

Diastole = ventricular/atrial relaxation

Cardiac Conduction System

SA Node

- crescent-shaped mass

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 - at epicardium of the posterior RA, next to crista terminalis and inferior to SVC entrance
- pacemaker: (70-80 pulses/min)

AV Node

- sits within the interatrial septum, posterior portion of RA

- delays conduction of signal by ~100msec

AV Node et al.

- Impulse travels from the AV node to the AV bundle

- The AV bundle travels along the interventricular septum and then divides to form the right
and left bundle branches (bundle of His)
- both branches form fine sub-endocardial fibres throughout the myocardium (Purkinje fibres)
– activation

Cardiac Conduction System

- The period between the start of one beat and the beginning
of the next is a cardiac cycle

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Autonomic Innervation of the Heart

Coronary Circulation – Arteries

Right coronary artery

- Posterior interventricular artery

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 - Marginal branch

Left coronary artery

- Anterior interventricular branch, aka left anterior descending (LAD) artery

- Circumflex branch

Coronary Circulation – Veins

Lecture 2 (a): Blood Vessel Characteristic

Learning Outcomes
- Describe the three tunics that form the wall of an artery or vein.
- Define vasa vasorum.
- Compare and contrast the structure and functions of elastic arteries, muscular arteries, and
arterioles.

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 - Describe the structure and function of capillaries, sinusoids, and capillary beds, and
explain the structural basis of capillary permeability.
- Describe the structural features of arteries and veins that help maintain the flow of blood
through these vessels.
- Define vascular anastomoses and explain their functions.
Blood Vessels
- Arteries
o transport blood away from the heart
o divide into smaller arterioles
- Capillaries
o allow exchange between blood and tissues
- Veins
o return blood to the heart
o originates from smaller venules

Blood Vessel Layers

- Tunica intima: a single endothelial layer in direct contact with blood flow
- Tunica media: smooth muscle layer
- Tunica adventitia/externa: connective tissue covering

Elastic and Muscular Arteries

Elastic
- largest arteries in the body (25-10 mm)
- conducting arteries
- close to the heart
- pressure reservoir

Muscular
- medium-sized arteries (10- 0.3 mm)
- distributing arteries

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 - vasoconstriction and vasodilation
- well-defined internal and external elastic membrane

Arterioles
- Smallest arteries (0.3-0.01 mm)
- Large arterioles contain all 3 tunics
- Small arterioles: endothelium + tunica media
- Local factors and sympathetic nervous system determine
diameter

Capillaries
- Smallest blood vessels (8-10 μm)
- found near almost every cell in the body
- 3 types: continuous, fenestrated or sinusoidal

Continuous
- most common
- least permeable

Fenestrated
- intermediate permeability
- contain
pores
- kidneys, small intestines

Sinusoidal
- most permeable
- larger diameter, twisted
- bone marrow, spleen

Mechanisms
of Capillary permeability
- direct diffusion through endothelial membrane
- intercellular clefts
- fenestrations
- pinocytic vesicles

Blood Brain Barrier

- low permeability
- selective transporters

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Structural Comparison of Arteries and Veins

Capillary Beds

Venules and Veins

Venules
- drain the capillary blood
- postcapillary venules – endothelium + pericytes
- larger venules: tunica media

Veins
- have same essential three layers as arteries, but…
- lumen larger
- tunica externa thicker than tunica media
- less elastin
- Valves formed from tunica intima

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Anastomoses
- ‘coming together’
- connections between arteries: arterial anastomoses
- collateral channels: alternative pathways for blood to reach an organ in the event of
blockage/severing of an artery
- common around joints
- veins > arteries

A Comparison of Blood Vessel Features

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Lecture 2 (b): Blood Vessel Pulmonary Circuit and Systemic Arteries
Pulmonary Circulation

arteries carry oxygen-poor blood to lungs

veins carry oxygen-rich blood to heart

Systemic Arteries
- aorta: largest artery
- four principal divisions of aorta
o ascending aorta

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 o arch of the aorta
o descending aorta (thoracic and abdominal parts)
- terminates at the L and R common iliac arteries

Ascending Aorta
- Ascending aorta branches into R and L coronary arteries

Aortic Arch
- brachiocephalic trunk: right subclavian artery + right common carotid artery
- left common carotid artery
- left subclavian artery

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Arteries of the Head and Neck
- four pairs of arteries supply the head and neck

Common Carotid Arteries

- Origin right: terminal branch of
brachiocephalic trunk left: branch of
aortic arch
- Course ascends lateral to trachea and
larynx
- Termination divides into external and
internal carotid arteries at the
superior border of larynx

External Carotid Arteries

- numerous branches supply tissue external to brain and orbit:

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 - superior thyroid artery
o thyroid gland and larynx
- lingual artery
o tongue
- facial artery
o anterior face
- occipital artery
o posterior scalp
- superficial temporal artery
o rest of scalp
- maxillary artery
o teeth, cheeks, nasal cavity, & muscles
of mastication

Internal Carotid Arteries

- branches supply orbits and cerebrum
- enters skull through carotid canal
- ophthalmic artery
- anterior cerebral artery
- anterior communicating artery
- middle cerebral artery

Vertebral Arteries
- branch of subclavian arteries
- ascend through foramina of C6 to
C1
- enter skull through foramen
magnum

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Cerebral Arterial Circle
- formerly called
the circle of Willis
- forms a loop
around pituitary
gland and optic
chiasma

Thyrocervical and Costocervical Trunks

Thyrocervical trunk:

- scapular muscles
- thyroid gland
- cervical vertebrae
- spinal cord

Costocervical trunk:

- deep muscles of neck

- 2 most superior intercostal space

Arteries of the Thorax

- A pair of superior phrenic arteries supply the superior, posterior diaphragm
- viscera of the thorax receive their blood from small branches from thoracic aorta

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Arteries of the Upper Limbs
- thoracoacromonial artery: pectoralis and deltoid muscles
- lateral thoracic artery: pectoralis and serratus anterior muscles; breast
- subcapsular artery: dorsal and ventral scapular regions; latissimus dorsi muscle
- circumflex humeral arteries: deltoid muscle and shoulder joint

Arteries of the Upper Limbs

- brachial artery
o muscles of anterior arm
- deep artery of the arm
o triceps
- radial artery
o muscles of the lateral anterior forearm
o lateral part of the wrist
o thumb and index finger
- ulnar artery
o muscles covering the ulna anterior
interosseus artery
o deep flexor muscles posterior interosseus
artery
o extensors of posterior forearm

Arteries of the Abdomen

- arise from abdominal aorta
- contain ~50% of arterial blood at rest

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Arteries from the Celiac Trunk
- viscera of the superior part of the abdominal trunk

Mesenteric
Arteries
- Superior mesenteric artery serves most of the intestines

Arteries of the Pelvis

- pelvic walls and viscera

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 - buttocks
- medial thighs
- perineum

Arteries of the Lower Limbs

Lecture 2 (c): Blood Vessel Systemic Veins

Learning Outcomes
- Define pulmonary and systemic circuits.
- Name the major vessels of the pulmonary circuit.
- Name the three vessels that arise from the aortic arch.
Describe the routes of arterial blood supply from these
vessels to the head and neck, the brain, the thorax, and
the upper limb.
- Describe the pathways and the organs supplied by the
midline arteries and by the paired arteries branching off
the abdominal aorta.
- Describe the pathway of arterial supply to the pelvis and
the lower limb.
- Trace the veins that empty into the superior vena cava as
you describe the routes of
venous return from the brain, the head and neck, and
the thorax and upper limbs.

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 - Trace the veins that empty into the inferior vena cava as you trace venous return from the
abdominal organs and from the pelvis and lower limbs.
- Describe the structure and special function of the hepatic portal system and explain the
significance of portal-systemic anastomoses.
Veins
- may be superficial or deep
- deep veins generally travel alongside arteries (and have similar names)
- superficial veins are clinically important for withdrawing blood
- multiple parallel veins; anastomosis of these: venous plexus
Venae Cavae

Veins of the Head and Neck

- Dural Venous Sinuses: endothelium-lined channels supported by dura mate

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Veins of the Thorax

Veins of the Upper Limbs

Veins of Abdomen

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Hepatic Portal System

Veins of the Pelvis and Lower Limbs

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Lecture 4: The Lymphatic System
Learning Outcomes
- Describe the structure and distribution of lymphatic vessels.
- Explain how lymph forms and the mechanisms by which it is transported.
- List and explain the important functions of the lymphatic vessels.
- Describe how lymph nodes function as
lymphatic organs.
The Lymphatic System
- primary functions:
o return of excess tissue fluids back to
the vascular system
o return of leaked blood proteins
back into the vascular syste
o fluid in the lymphatic vessels is
known as lymph
o only flows toward the heart
Lymphatic Capillaries
- highly permeable
- single layer of endothelial cells

Collecting Lymphatic Vessels

- contain tunica intima, tunica media
and tunica externa lower pressure
than veins – more valves than veins

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Lymph Nodes
- critical for eradication of pathogens that enter lymph from tissues ~500 lymph nodes in the
body 1 to 25 mm in diameter

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Lymph Trunks and Ducts

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Lecture 5: Respiratory System
Learning Outcomes
- Identify the respiratory passageways in order, from the nose to the alveoli in the lungs.
- Distinguish the structures of the conducting zone from those of the respiratory zone
- Describe the special features of the respiratory epithelium
- Identify the muscles involved in pulmonary ventilation
- Identify structures that make up the external nose and internal nasal cavity, and describe
how the structure of these features contribute to their functions
- Identify the boundaries of the three regions of the pharynx and the structures located in
each region
- List and describe the numerous structures in the upper airways that protect the respiratory
system from dust, bacteria, food particles, and/or other foreign matter
- Identify the structures of the larynx
- Identify the anatomical structures of voice production
- Describe the gross and microscopic structure of the trachea
- Identify anatomical structures of the bronchial tree
- List and describe the numerous structures that protect the lower respiratory system from
dust, bacteria, food particles, and/or other foreign matter
- Describe the gross structure of the lungs
- Describe the structure of a lung lobule
- Describe the structures and cells that make up the respiratory membrane

The Respiratory System

- Overview of the Respiratory System
- The Upper Airways
- The Respiratory Tract
- The Respiratory Zone

Structures of the Respiratory System

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Functions of the Respiratory System
- Principal function is gas exchange
- The respiratory system also:
o regulates blood pH
o contains receptors for olfaction
o filters inhaled air
o produces sounds
o rids the body of small amounts of water and heat in exhaled air

Structures of the Respiratory System

functionally divided into the

conducting and respiratory
zones

Respiratory Epithelium

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Muscles of Pulmonary Ventilation

The Upper Airways

The External Nose

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The Nasal Cavity
Functions of the Nasal Cavity

- Passageway for air

- Contains structures to warm, filter, and moisten
air
- Connected to the paranasal sinuses
- Nasal cavity is divided into two halves by nasal
septum
- Each side of the nasal cavity is subdivided into a
series of groove-like passageways
- Superior meatus
- Middle meatus
- Inferior meatus

The Nasal Septum

- The nasal septum is formed by the septal nasal
cartilage, attaching to the vomer and
perpendicular plate of the ethmoid bone

Nasal Cavity: Concha and Meatus

- Functions: WARM, FILTER, and MOISTEN AIR
- Nasal concha are long, narrow and curled bone
that protrudes into the nasal cavity.
o Covered in respiratory epithelium
- Nasal meatus are the passageways for air
created by the protruding concha
- Connected to the paranasal sinuses
- Lined with Respiratory Epithelium

The Paranasal Sinuses

Functions of the paranasal sinuses

- Passageway for air

- Warm and moisten air
- Continuous with the nasal cavity lined with respiratory
epithelium

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The Pharynx
Functions of the pharynx (throat)

- Passageway for air, food and

fluid
- Provides a resonating chamber
for speech sounds
- Houses the tonsils

Can be divided into three anatomical

regions:

- Nasopharynx* contains
pharyngeal tonsil or adenoid
- Oropharynx** contains palatine
and lingual tonsils
- Laryngopharynx** begins at
hyoid bone
o *lined with respiratory epithelium
o **lined with stratified squamous
epithelium

The Larynx
Functions of the larynx (“voice box”)

- Connects laryngopharynx with trachea

- Houses the vocal cords
- Transition point from upper airways into the
respiratory tract
- The cylindrical wall of the larynx is composed of
nine pieces of cartilage
o Three occur singly (thyroid cartilage,
epiglottis, and cricoid cartilage)
o Three occur in pairs (arytenoid,
cuneiform, and corniculate cartilages

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The Epiglottis
Elastic “leaf-shaped” cartilage that closes off the larynx

- Essentially a valve
- Stratified squamous epithelium on pharyngeal side
(contact with food and fluid)
- Respiratory epithelium on laryngeal surface

Bronchial Tree

Airway Branching

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The Trachea

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The Lungs

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Right Lung

Left Lung

Medial View

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The Respiratory Zone

Left Lobule

Alveoli Sac

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Many Alveoli, One Alveolus

Respiratory Membrane

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