05 NBHS1113 T1 PDF

Topic  The Human
Body:
1 Introduction
to Anatomy
and Body
Organisation
By the end of this topic, you should be able to do the following:

1. Describe the six levels of body organisation in our body.
2. Identify the main organ systems of our body.
3. Describe the different levels of organisation in our body.
4. Discuss the descriptive terms of anatomy.
Let us all sit up straight, take a deep breath and feel the air enter our lungs.
Imagine the passage of air from your nose into your lungs and back out again.
Still sitting up straight, put the palms of your hands on your knees and then,
gently tap your fingers on your knees. How many parts of your body can you
feel? Can you feel the muscles of your thighs? How about feeling your elbow
Copyright © Open University Malaysia (OUM)

2  TOPIC 1 THE HUMAN BODY: INTRODUCTION TO ANATOMY
AND BODY ORGANISATION
joints and your shoulder muscles as you move your hands to your knees?
Can you imagine the number of motions in the body as your fingers gently tap
on your knees?
We are an incredibly complex union of parts. Our function and survival are
dependent on all these parts working together towards a common goal. For this
to be successful, all the parts that form our body have to be of specific shape
and size, work in a predictable manner and communicate with each other.
To allow this to happen, our bodies are built on an organisational basis, with
an increasing hierarchy of size and complexity from the level of the cell to the
entire body. The study of the function of our body (how it works) is called
physiology, while the study of the form of our body (how it looks, what it is
made of) is termed anatomy.
1.1 ANATOMY
Anatomy is the bodyÊs form and structure. Studying anatomy involves the
learning of the names of the various parts of our body and the location of the
various organs and systems in our body. The study of anatomy also examines
the relationship between the structure of our body and the functions of our
body. To study physiology is to study the biological and chemical processes
that occur in the body.
Anatomy can be approached from a number of perspectives. Generally, anatomy

is divided into the following categories:
(a) Gross Anatomy

Gross anatomy, also called macroscopic anatomy, covers large body
features that are visible to the naked eye. The study of gross anatomy can be
divided into:
• regional anatomy: the study of all the structures in a particular region

of the body;
• systemic anatomy: the study of the body system by system; and
• surface anatomy: the study of the external form of the body and its
relationship to deeper structures.

TOPIC 1 THE HUMAN BODY: INTRODUCTION TO ANATOMY  3
(b) Microscopic Anatomy

This is the study of body structures too small to be seen by the naked eye.
Microscopic anatomy is generally divided into two groups:
• cytology: the study of cells; and
• histology: the study of body tissue.
The most common approach to studying anatomy is using diagrams or

photographs of the body. Advancement in imaging technology has enabled us
to view our body structures without surgery, called non-invasive surgery.
Among the popular imaging technology used includes X-ray, ultrasound,
magnetic resonance imaging (MRI), computed tomography scan (CT scan) and
computed axial tomography scan (CAT scan).
1.2 BODY ORGANISATION

To understand body organisation, we must first understand what biologists
refer to as the characteristics of life. Biologists consider life to have a number
of characteristics. These are generally summarised in Figure 1.1 as follows:
Figure 1.1: Characteristics of Living Things

These characteristics of life determine the development of the various structures

of our bodies. Specialised cells, for example, develop to perform specialised
functions such as reproduction, while organ systems develop to perform functions
like movement. The organism as a whole is a collection of parts that allows
all the above characteristics of life to be displayed.
Organisation is one of the most important characteristics of life. By approaching

life from an organisational point of view, we are able to study it and to understand
the basic functions of our bodies. In the study of anatomy, organisation is viewed
from the cellular level to the organism level. The main levels in the study of
anatomy (see Figure 1.2) can be summarised as follows:
(a) Molecular or Chemical Level

Many molecules play a vital role in life processes and their structure is
important in determining their functional characteristics. These range from
the organic molecules that make up life (like structural phospholipids) to
inorganic molecules needed for various life processes (like the oxygen
molecules carried by our blood).
(b) Cellular Level

Cells are the basic units of life. Molecules combine to form organelles,
which in turn form the functional units of cells.
(c) Tissue Level

A tissue is formed from an aggregation of cells. Most of the specialised
functions of the body are carried out by tissues.
(d) Organ Level

Organs are made up of tissues. An organ is composed of two or more tissue
types that perform common functions. Examples include the skin, heart
and urinary bladder.
(e) Organ System Level

An organ system is a group of organs performing a set of related functions
as a unit. Several organs make up an organ system. This course is based on
the study of selected organ systems. Examples include the skeletal system
and nervous system.
(f) Organism Level

An organism is a whole collection of functional parts displaying the
characteristics of life. Some organisms are simple unicellular creatures
with no organ systems but they still display all the characteristics of life.
For the study of human anatomy, though, we look into the human organism
which is a large multi-cellular mammal made up of several organ systems.

Figure 1.2: Levels of Organisation of the Human Body
Source: Seeley, Stephens & Tate (2003)

This organisational hierarchy allows for the development of high levels of

complexity as different levels of organisation cooperate to produce a single
individual. We will explore the basic features of cells and tissues, and then the
organ systems. The study of anatomy is rarely approached from the perspective
of individual organs. Rather, organs are studied in detail as parts of functional
organ systems. Nevertheless, there are a number of vital organs in the human
body such as the heart, lungs, kidneys, liver, brain and stomach.
1.3 ORGAN SYSTEMS

In this course, we will approach human anatomy and physiology from an
organ system perspective. There are 11 major organ systems in the human body:
• integumentary system
• skeletal system
• muscular system
• nervous system
• endocrine system
• cardiovascular system
• lymphatic system
• respiratory system
• digestive system
• urinary system
• reproductive system
The organ systems can be grouped into four categories according to the functions
they perform. These categories are:
• support and movement systems that include the integumentary system,

skeletal system and muscular system;
• integration and control systems that include the nervous system, sense organs
and endocrine system;

• regulation and maintenance systems that include the cardiovascular system,

lymphatic system, respiratory system, digestive system and urinary system;
and
• reproductive systems that are differentiated into the female and the male
reproductive systems.
These systems function in a complex and coordinated way to keep us alive.

Though each system has its own functions and set of organs, the functions (and
sometimes the organs) overlap between systems and each system is dependent
on other systems for its function. The end result is a smooth running multi-system
organism of high organisation and complexity.
1.4 STUDYING HUMAN ANATOMY AND

BODY ORGANISATION
Anatomy is a descriptive science. It is about names and locations and is full of
details. However, you should not try remember all the details at once. Rather,
attempt to approach the course in a systematic manner. Take an organ system
by organ system approach, and break down each topic into manageable units
of study. Try to remember the relationship between the different structures
you are studying and associate this with their function. This will often help you
to remember the names of structures.
Descriptive terms in anatomy can be summarised into six groups according to

what aspects of the body they describe. These are:
• body positions
• directional terms
• planes of visualisation
• body parts and regions
• body cavities
• serous membranes
Let us now learn about these groups in more depth.

1.5 BODY POSITIONS

There are three basic positions used in anatomy. These are:
(a) Anatomical Position

This refers to a person standing erect with his face directed forward,
his upper limbs hanging to his sides, and the palms of his hands facing
forward. This is the position in which most figures in this module will
represent the human form.
(b) Supine Position

This refers to a person lying face upwards and the arms on the side of
their body. This is a position commonly used in surgical procedures
performed on the abdomen because it allows access to the major body
cavities.
(c) Prone Position

This refers to a person lying with his face downwards.
The position of the body determines the relative position of the various body
parts. As a rule, all directional definitions in the study of the anatomy are
based on the anatomical position (so the elbow, for example, is always above
the hand).
SELF-CHECK 1.1
Define anatomical position.
1.6 DIRECTIONAL TERMS

Directional terms are extremely important in the study of anatomy and you will
find that by understanding the use of these terms, you can even begin to guess
at the function of different organs and tissue. Table 1.1 summarises the major
directional terms used in the study of anatomy and Figure 1.3 provides a
diagrammatic representation of them. The most important terms to remember
are superior (up), inferior (down), anterior (front), posterior (back), proximal
(nearer) and distal (farther). Remember that all directional terms are based on
a person being in the anatomical position.

Table 1.1: Directional Terms
Term Definition Example
Superior Towards the head end

(Cranial) or upper part of a
structure or the body;
The head is
above
superior to the
abdomen
Inferior Away from the head end

(Caudal) or towards the lower part
of a structure or the body;
The navel is
below
inferior to the
chin
Anterior Towards or at the front

(Ventral) of the body; in front of The breastbone
is anterior to
the spine
Posterior Towards or at the back

(Dorsal) of the body: behind The heart is
posterior to
the breastbone
Medial Towards or at the midline

of the body; on the inner
The heart is
side of
medial to the
arm

Lateral Away from the midline

of the body; on the outer
The arms are
side of
lateral to the
chest
Intermediate Between a more medial The collarbone

and a more lateral is intermediate
structure between the
breastbone and
shoulder
Proximal Closer to the origin of

the body part or the
point of attachment of
The elbow is
a limb to the body trunk
proximal to the
wrist
Distal Father from the origin

of a body part or the
point of attachment of
The knee is
a limb to the body trunk
distal to the
thigh
Superficial Towards or at the body The skin is

(external) surface superficial to
the skeletal
muscles
Deep Away from the body

(internal) surface; more internal
The lungs are
deep to the skin
Source: Marieb (2004)

Figure 1.3: Directional Terms Used in the Study of Human Anatomy
In animal anatomy, the words cephalic (towards the head or superior) and
caudal (towards the tail, or inferior) are often encountered, as well as ventral
(that which goes before, or anterior) and dorsal (that which follows, or
posterior). These would still be used to refer to an animal in the anatomical
position (a fish, for example, would be standing on its tail with the belly facing
forward).
SELF-CHECK 1.2
Differentiate between superior, inferior, anterior, posterior, distal and

proximal.

1.7 PLANES OF VISUALISATION

Planes are imaginary flat surfaces used to divide the body into sections to
allow the observer to „look inside‰ the body. Most anatomical drawings you
encounter are based on this concept. There are three basic planes used for
visualisation of the human anatomy. These are summarised in Figure 1.4 and
include the following:
(a) Sagittal Plane

This plane runs vertically through the body and perpendicular to the
ground, separating the body into left and right portions. A midsagittal
or median plane runs through the midline (centre) of the body and divides
it into equal left and right halves; while a parasagittal plane divides the
body into unequal left and right halves as it runs vertically through the
body to one side of the midline (not through the centre).
(b) Transverse or Horizontal Plane

This plane runs through the body horizontally and parallel to the ground,
dividing the body into superior and inferior portions.
(c) Frontal or Coronal Plane

This plane runs vertically from right to left, perpendicular to the ground
and divides the body into anterior and posterior portions.

Figure 1.4: Planes of Visualisation of the Body
When organs or parts of the body are sectioned to reveal their internal structure,
this is often done along specific planes of visualisation (as shown in Figure 1.5).
In this case, you are likely to encounter three planes of sectioning. These are:
(a) Longitudinal Section

This is a section cut through the long axis of an organ.
(b) Cross-section or Transverse Section

This is a section cut at a right angle to the long axis.

(c) Oblique Section

This is a section cut across the long axis but at an angle that is not a right
angle (imagine it as a cross-section at an angle).
Figure 1.5: Planes of Section through an Organ
Remember that all planes of visualisation, like other descriptive anatomical

terms, are based on the body in the standard anatomical position.

1.8 BODY PARTS AND REGIONS

Specialised terms are used in the study of anatomy to refer to different parts of
the body. There are several of these terms, and many of them, like „arm‰, are also
used in common everyday speech. There are too many of these terms to list and
describe individually and they are best illustrated diagrammatically. Figure 1.6(a)
and (b) shows the majority of these terms as used in anatomy. Some of the
important ones can be summarised as follows:
• the arm extends from the shoulder to the elbow;
• the forearm extends from the elbow to the wrist;
• the thigh extends from the hip to the knee;
• the leg extends from the knee to the ankle;
• the head, neck and trunk make up the central region of the body;
• the trunk can be divided into the thorax, abdomen and pelvis;
• the thorax refers to the chest;
• the abdomen refers to the region between the thorax and the pelvis; and
• the pelvis refers to the inferior end of the trunk associated with the hips.

Figure 1.6: Common and Anatomical Names of Major Body Parts and Sections

However, it is important to remember that in the study of the anatomy, these terms
have very specific meanings and are restricted in their use and scope, unlike in
common speech where we use these terms in both specific and general contexts.
For example, in the study of human anatomy, the term „arm‰ refers to the
body part extending from the shoulder to the elbow, while the term „forearm‰
refers to the extension from the elbow to the wrist. In common speech, we often
use „arm‰ (or even worse, „hand‰) to refer to the whole structure, from the
shoulder to the wrist and beyond. As such, it is vital for you to keep the
anatomical restrictions of the use of body part names in mind at all times.
SELF-CHECK 1.3
List three major body parts and describe their locations on the human
body.
1.9 BODY CAVITIES

Many important organs are suspended in internal chambers called body cavities
and these body cavities have two vital functions. Firstly, they shield organs
against accidental shocks and cushion them from sudden impacts as a result
of jumping or running. Secondly, they allow significant changes in the size and
shape of internal organs such as allowing the lungs to expand and contract
without distorting the surrounding tissues or disrupting the activities of nearby
organs. The human body has two major body cavities – dorsal and ventral
(see Figure 1.7).

Figure 1.7: Cavities of the Trunk
Source: Seeley, Stephens, & Tate (2003)
(a) Dorsal Body Cavity

This is a fluid-filled space that protects nervous system organs. It is divided
into two subdivisions – cranial cavity (in the skull, encasing the brain)
and spinal cavity (which encloses the spinal cord).
(b) Ventral Body Cavity

This cavity has two major subdivisions – thoracic cavity and abdominopelvic
cavity. The thoracic cavity is surrounded by the ribcage and is separated
from the abdominal cavity by the diaphragm. The thoracic cavity is divided
by a median partition called the mediastinum into the right and left
portions. Our two lungs are located on either side of the mediastinum.
Within this mediastinum lie several organs including the esophagus,
trachea, heart and thymus gland, as well as some major blood vessels and
nerves. The abdominal cavity is inferior (lies below) to the thoracic cavity
from which it is separated by the diaphragm. It is enclosed by abdominal
muscles and contains some of the largest organs in our body including
intestines, liver and stomach, as well as spleen, pancreas and kidneys.

The pelvic cavity is a small cavity enclosed by pelvic bones and contains
the internal reproductive organs, urinary bladder and a small distal part of
the large intestine. Since the abdominal and pelvic cavities are not physically
separated, they are often referred to together as the abdominopelvic cavity.
SELF-CHECK 1.4
List three major organs and describe the body cavity they are located
in.
1.10 SEROUS MEMBRANES

Serous membranes are protective membranes that line the inside of the trunk
cavities and enclose the organs of the trunk cavities. Serous membranes occur
in pairs with the visceral serous membrane being the inner membrane in contact
with the organ and the parietal serous membrane being the outer membrane in
contact with the cavity wall. The space between the two membranes is filled
with serous fluid secreted by the membranes. This fluid forms a thin lubricating
film that protects the organs and reduces friction between the organs as they
rub against each other or the body wall.
The thoracic cavity contains three serous-lined cavities: the pericardial cavity
and two pleural cavities.
(a) The pericardial cavity contains the heart (Figure 1.8). The heart is
surrounded by the visceral pericardium which is itself surrounded by the
parietal pericardium. Between these two pericardia lies the pericardial
cavity that contains pericardial fluid.

Figure 1.8: Serous Membranes

(b) The two pleural cavities surround the lungs with one for every lung
(Figure 1.8). Each lung is covered by visceral pleura, while parietal pleura
lines the inner surface of the thoracic wall, the lateral surface of the
mediastinum and the superior surface of the diaphragm. Pleural fluid is
contained in the pleural cavity between these two membranes. The
abdominopelvic cavity contains the peritoneal cavity, which is lined by
serous membranes. The visceral peritoneum lines most of the organs of
the abdominal cavity, while the parietal peritoneum lines the inferior
surface of the diaphragm and the walls of the abdominopelvic cavity.
Between these two membranes is the peritoneal cavity filled with peritoneal
fluid.
A specialised type of serous membrane formation called the mesentery anchors

or connects the visceral peritoneum of many abdominopelvic organs to the
visceral peritoneum of other abdominopelvic organs or to the parietal peritoneum
of the body wall (see Figure 1.7). Mesenteries consist of two layers of fused
peritoneum, and other than acting as an anchor, also serve as a pathway for
many blood vessels and nerves.
Some organs of the abdominopelvic cavity, like the kidneys, the urinary bladder
and the pancreas, are anchored directly to the body wall and do not possess a
covering of visceral peritoneum. Instead, they are covered only by the parietal
peritoneum. Such organs are said to be retroperitoneal.
SELF-CHECK 1.5
What are serous membranes? Name two serous membranes.

• Anatomy is the study of the bodyÊs form and structure. It is divided into
gross anatomy, also called macroscopic anatomy and microscopic anatomy.
• The main levels of organisation relevant to the study of anatomy are the
molecular level, cellular level, tissue level, organ level, organ system level
and organism level.
• Descriptive terms in anatomy can be summarised into six groups according to

the aspects of the body they describe. These are body positions, directional
terms, planes of visualisation, body parts and regions, body cavities and
serous membranes.
• There are three basic positions used in the study of the anatomy – anatomical
position, supine position and prone position.
• The most important directional terms in the study of the anatomy are
superior (up), inferior (down), anterior (front), posterior (back), proximal
(nearer) and distal (farther).
• There are three basic planes of visualisation in anatomy – sagittal plane,

transverse or horizontal plane, and frontal or coronal plane.
• In the study of anatomy, terms have specific meanings and are restricted in
their use and scope, unlike common speech.
• Body cavities are chambers that house the important organs.
• Serous membranes are protective membranes that line the inside of the
trunk cavities and enclose the organs of the trunk cavities.

Anatomy Gross anatomy

Body cavities Microscopic anatomy
Body organisation Organ system
Body parts and regions Physiology
Body positions Planes
Directional terms Serous membranes
Seeley, R. R., Stephens, T. D., & Tate, P. (2003) Anatomy and physiology.
McGraw-Hill.

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Topic  The Human

By the end of this topic, you should be able to do the following:

Copyright © Open University Malaysia (OUM)

Anatomy can be approached from a number of perspectives. Generally, anatomy

(a) Gross Anatomy

• regional anatomy: the study of all the structures in a particular region

• systemic anatomy: the study of the body system by system; and

Copyright © Open University Malaysia (OUM)

(b) Microscopic Anatomy

• cytology: the study of cells; and

• histology: the study of body tissue.

The most common approach to studying anatomy is using diagrams or

1.2 BODY ORGANISATION

Figure 1.1: Characteristics of Living Things

Copyright © Open University Malaysia (OUM)

These characteristics of life determine the development of the various structures

Organisation is one of the most important characteristics of life. By approaching

(a) Molecular or Chemical Level

(b) Cellular Level

(c) Tissue Level

(d) Organ Level

(e) Organ System Level

(f) Organism Level

Copyright © Open University Malaysia (OUM)

Figure 1.2: Levels of Organisation of the Human Body

Source: Seeley, Stephens & Tate (2003)

Copyright © Open University Malaysia (OUM)

This organisational hierarchy allows for the development of high levels of

1.3 ORGAN SYSTEMS

• support and movement systems that include the integumentary system,

Copyright © Open University Malaysia (OUM)

• regulation and maintenance systems that include the cardiovascular system,

These systems function in a complex and coordinated way to keep us alive.

1.4 STUDYING HUMAN ANATOMY AND

Descriptive terms in anatomy can be summarised into six groups according to

• body parts and regions

Let us now learn about these groups in more depth.

Copyright © Open University Malaysia (OUM)

1.5 BODY POSITIONS

(a) Anatomical Position

(b) Supine Position

(c) Prone Position

Define anatomical position.

1.6 DIRECTIONAL TERMS

Copyright © Open University Malaysia (OUM)

Table 1.1: Directional Terms

Term Definition Example

Superior Towards the head end

Inferior Away from the head end

Anterior Towards or at the front

Posterior Towards or at the back

Medial Towards or at the midline

Copyright © Open University Malaysia (OUM)

Lateral Away from the midline

Intermediate Between a more medial The collarbone

Proximal Closer to the origin of

Distal Father from the origin

Superficial Towards or at the body The skin is

Deep Away from the body