1. INTRODUCTION TO THE HUMAN BODY

INTRODUCTION TO
THE HUMAN BODY

AAP2013

LEARNING OUTCOME

 After studying this section, students should be able to :
1. Define common anatomical terms.
2. Describe the roles of the body transport systems.
3. Outlines the roles of the nervous and endocrine

systems in internal communication
4. Explain how raw materials are absorbed by the body
5. State the waste materials eliminated from the body

DEFINITION OF ANATOMY & PHYSIOLOGY

 Anatomy and physiology are two of the most basic terms and
areas of study in the life sciences.

 Anatomy refers to the internal and external structures of the
body and their physical relationships, whereas physiology refers
to the study of the functions of those structures.

 A single organism is composed of billions and trillions of
cells, tissues, and organs. These structures include both
microscopic and macroscopic. Cells are microscopic
structures which are examined only under the electronic
microscopic, whereas organs and organ systems are
macroscopic structures which can be easily seen through
our naked eye.

Anatomy

 There are several branches of human anatomy.
• Macroscopic or Gross anatomy
 This anatomy mainly deals with the study of large body parts

those which can be seen easily through our naked eyes. For
example Anatomy of the kidney, anatomy of the heart,
anatomy of lungs, etc. Gross anatomy is further classified into
regional anatomy, systemic anatomy, and surface anatomy.
1. Regional anatomy: A study of different structures in a
particular region.
2. Systemic anatomy: A study of human structures, the system by
system.
3. Surface anatomy: A study of only internal structures of a
human body.

Microscopic anatomy

 This anatomy mainly deals with the study of very small
and minute structures those which can only be
examined through the microscope. For example
Different types of cells.

 is further classified into cytology and histology.

❖ -Cytology deals with the study of human blood cells

❖ -Histology deal with the study of different tissues in the
human body.

Developmental Anatomy

 mainly used to study the different structural changes in
the body which occurs throughout the lifespan.

 Embryology developmental anatomy is used to know
completely about the development process before
childbirth.

Physiology

 Physiology is a branch of natural science and biology
which includes the study of the complete functioning
system of a body. It is further classified into:

1. System physiology: It is a study of the complete
functioning of body systems.

2. Comparative physiology: It is the study of various
characteristics of living organisms

3. Medical physiology: It is the study of physiological
dysfunctions and other diseases related to the functioning
of the human body systems.

LEVEL OF STRUCTURAL ORGANIZATION
OF THE HUMAN BODY

Level of structural complexity

 There are different level of structural organization
and complexity.

 The most fundamental of these is chemical.
 Atoms combine to form molecules.
 Cells are the smallest independent units of living

matter.
 Too small to seen with the naked eye.
 But, when magnified with using microscope different

type can be distinguished by size, shape.

Cont.

 Function of nerve cell is to transmit electrical signals (nerve
impulses).

 These are integrated and coordinated, allowing the million of
nerve cells in the body to provide a rapid and sophisticated
communication system.

 Cells forming tissue.

 Organs are made up of a number of different types of tissue and
carry out a specific function.

 There are around 80 organs, associated with one or more body
systems.

 System consist of a number of organs and tissues. Ex: stomach
and liver consider to be part of the digestive system.

Level of structural complexity

Cells forming Organs Body systems
tissues

COMMUNICATION

 Communication systems receive, collate and respond
to information that may originate either within the
body (internally) or from its environment (externally)

 Internal communication involves mainly the nervous
and endocrine systems; these are important in the
maintenance of homeostasis.

Transport systems

1. Blood
2. Cardiovascular system
3. Lymphatic system

Blood

 Blood transports substances around the body
through a large network of blood vessels.

 In adults the body contains 5-6 litres of blood
 Consist of two part:
1. Plasma
2. Blood cells

Plasma :

 90% water include:

1. Nutrients absorbed from the
alimentary canal

2. Oxygen absorbed from lungs

3. Chemicals synthesised by
body cells e.g hormones

4. Waste materials produced by
all cells to be eliminated
from the body by excretion.



Blood cells

 There are 3 group:

1. Erythrocytes (red blood cells) -
transport oxygen

2. Leukocytes (white blood cells) –
protection of the body against
infection and foreign substances.

3. Platelets (thrombocytes) – blood
clotting

Cardiovascular system

 Consists of a network of
blood vessels and the heart.

 Blood vessels – three types:
1. Arteries – carry blood away

from the heart
2. Veins – return blood to the

heart
3. Capillaries – link the arteries

and veins.



 Blood vessel form a massive
network that transport blood
to:

1. The lungs (pulmonary
circulation) –oxygen is
absorbed from the air in the
lungs at the same time carbon
dioxide is excreted from the
blood into the air.

2. Cells in all other parts of the
body

Heart

 The heart is a muscular sac with four chambers, which
pumps blood round the body and maintains the blood
pressure.

 at rest, the heart contracts or beats between 65 and 75
times per minute.

 The rate increases when body oxygen requirements are
increased, e.g during exercise.

 Rate of heart beats can be counted by taking the pulse.



Lymphatic system

1. Lymph is tissue fluid that also contains material drained
from tissue spaces including plasma proteins and
sometimes bacteria or cell debris.

2. Transport along lymph vessels and returned to the
bloodstream near the heart.

3. Lymph is filtered as it passes through these nodes,
removing microbes and other materials.

4. Other lymphatic organ include the spleen and the thymus.

5. Also provide the sites for formation and maturation of
lymphocytes, the white blood cells involved in immunity.

Internal Communication with
communication the external
environment
1. Nervous system
2. Endocrine system 1. Special senses

2. Verbal
communication

3. Non-verbal
communication

Internal communication

 Nervous system –rapid communication system
 Central nervous system consist of:
1. Brain – situated inside the skull
2. Spinal cord – extend from the base of the skull to

the lumbar region (lower back).
 -spinal cord is protected from injury as it lies

within the bones of the spinal column.

 -peripheral nervous system is a network of nerve fibres,
which are either:

1. Sensory or afferent nerves – transmit signals from the
body to the brain or

2. Motor or efferent nerves – transmit signals from the
brain to the effector organs, such as muscles and glands.

▪ Somatic (common) sense – pain, touch, heat and cold.

▪ These sensation arise following stimulation of specialised
sensory receptors at nerve endings found throughout the
skin.

 Sensory receptors are activated by stimuli in internal

organs and control vital body functions e.g heart rate,

respiratory rate and blood pressure.

 Reflex action are fast, involuntary, and usually protective
motor responses to specific stimuli. They include:

1. Withdrawal of a finger from a very hot surface
2. Constriction of the pupil in response to bright light
3. Control of blood pressure





Endocrine system

 Consist of number of discrete glands situated in
different parts of the body.

 Synthesise and secrete chemical messengers
called hormones that ciculate round the body in
the blood.

 Hormones stimulate target glands or tissues,
influencing metabolic and other cellular activities
and regulating body growth and maturation.

Special senses

 Stimulation of specialised receptors in sensory
organs or tissues given rise to the sensations of
sight, hearing, balance smell and taste.

 One sense is rarely used alone.

 Example:

 When the smell smoke is perceived, other sense
such as sight and sound are used to try to locate
the source of fire – escape from fire.

 Taste and smell – food – prepare digestive system
subconsciously for eating.

Verbal communication

 Sound is produced in the larynx when expired air
coming from the lungs passes through and
vibrates the vocal cords

 In human, recognisable sounds produced by

▪ coordinated contraction of the muscles of the
throat and cheeks,

▪ and movement of the tongue and lower jaw –
known as speech

Non-verbal communication

 Posture and movement eg:
▪ nodding the head and shrugging the shoulders –

the skeleton
▪ Changes in facial expression – may not involve the

movement of bones.

Intake of oxygen

 Oxygen gas makes up about 21% of atmospheric
air.

 Oxygen is necessary for the series of chemical
reactions that result in the release of energy from
nutrients.

 Chemical energy is essential fuel for all cellular
activity.

 Upper respiratory systems carries air between the
nose and the lungs during breathing.

 Air passes through a
system passages,
including nasal cavity 
pharynx  larynx 
trachea  two bronchi 
large number of bronchial
passage  alveoli

Ingestion of nutrients (eating)

 Balanced diet is important for health and provides
nutrients, promote body function, including cell
building, growth and repair.

 Nutrients include water, carbohydrates, proteins,
fats, vitamins and mineral salts





Elimination of waste

1. Carbon dioxide – excreted through the lungs
during expiration

2. Urine – formed by the kidneys part o urinary
system

3. Faeces – excreted as faeces during defaecation



Protection against the external
environtment

 The skin forms a physical barrier against invasion
by microbes, chemical and dehydration

 Consist of two layers :epidermis ,dermis
1. Epidermis - superficial
2. Dermis contains tiny sweat gland, rich in sensory

nerve ending sensitive to pain, temperature and
touch, important role in the regulation of body
temperature.



Movement

 Essential for many body activities eg: obtaining
food, running from danger, avoiding injury and
reproduction

 Most body movement is under conscious
(voluntary) control.

 Except – protective movements (reflexes) that
carried out before the individual is aware eg: the
rapid withdrawal of the hand from a hot cooker

Musculoskeletal system

 Includes the bones of the
skeleton, skeletal muscles and
joints.

 Skeleton – provides rigid body
framework

 Movement take place at joints

 Skeletal muscle – maintain
posture and balance and move
skeleton.







Reproduction

 Successful reproduction is
essential to ensure the
continuation of a species
and genetic characteristics
from one generation to the
next.



Cavities of the body