Human Physiology
Lecture : 1 حسن.د
Introduction
Anatomy: is the study of structures that make up the body and how those structures relate with
each other.
Physiology: is the study of how the body and its parts work or function.
Level of structural organization of the body
The human body has different structural levels of organization, starting with atoms, molecules and
compounds and increasing in size and complexity to cells, tissues, organs and the systems that make
up the complete organism.
1) Atoms and molecules:
The body is composed of atoms. The most common atoms in living organism are carbon,
hydrogen, oxygen, nitrogen, phosphorus and sulfur.
2) Cell:
Cell is the smallest independent units of life. All life depends on the many chemical activities of
cells. Some of the basic functions of cell are: growth, metabolism, and reproduction.
3) Tissue:
Tissue is made up of many similar cells that perform a specific function. The various tissues of the
body are divided in to four types, these are:
a) Epithelial tissue: - Found in the outer layer of skin, lining of organs, blood and lymph vessels
and body cavities.
b) Connective tissue: - Connects and supports most part of the body. They constitute most part of
skin, bone and tendons.
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c) Muscle tissue: - Produces movement through its ability to contract. This constitutes skeletal,
smooth and cardiac muscles.
d) Nerve tissue: - Found in the brain, spinal cord and nerves. It responds to various types of
stimuli and transmits nerve impulses.
4) Organ:
Organ is an integrated collection of two or more kinds of tissue that works together to perform
specific function. For example: Stomach is made of all type of tissues.
5) System:
System is a group of organs that work together to perform major function. For example: Respiratory
system contains several organs.
6) Organism: - The various organs of the body form the entire organism (human body).
Anatomical Terminologies
A. Anatomical position:
In anatomical position the human subject is standing erect and facing the observer, the feet are
together, and the arms are hanging at the sides with the palms facing forward.
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B. Direction
al terms:
It is a standardized terms used when anatomists describe the location of the body part.
Term Definition Example
Superior (cranial) Toward the head. The leg is supper to the foot.
Inferior (caudal) Toward the feet. The foot is inferior to the leg.
Anterior (ventral) Toward the front part of the The nose is anterior to the
body. ears.
Posterior (dorsal) Towards the back of the The ears are posterior to the
body. nose.
Medial Towards the midline of the The nose is medial to the eyes
body.
Lateral Away from the midline of The eyes are lateral to the
the body. nose
Proximal Toward (nearer) the trunk of The shoulder is proximal to
the body or the attached end the wrist
of a limb.
Distal Away (farther) from the The wrist is distal to the
trunk of the body or the forearm.
attached end of a limb.
Superficial Nearer the surface of the The ribs are superficial to the
body. heart
Deep Farther from the surface of The heart is deeper to the
the body. ribs.
Peripheral Away from the central axis Peripheral nerves radiate
of the body. away from the brain and
spinal cord.
Central
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C. Body parts and regions:
The body can generally be described to have areas of:
1. Axial body part: -
It is the part of the body near the axis of the body.
This includes: Head, Neck, Thorax (Chest), Abdomen and Pelvis.
2. Appendicular body part: -
It is the part of the body out of the axis line.
This includes: Upper extremities ( arms, forearms, and hands) and Lower extremities ( thighs,
legs, and feet)
The abdomen is subdivided into nine regions or more easily in to four quadrants.
D. Body planes and sections:
Body planes are imaginary planes that divide the body into sections. These are:
1. Sagittal plane: divides the body into right and left half.
Mid sagittal plane: - divides body into equal left and right halves.
Para sagittal plane: - divides body into unequal left and right
2. Frontal plane: - divides the body into asymmetrical anterior and posterior sections.
3. Transverse plane: - divides the body into upper and lower body section.
4. Oblique plane: - divides the body obliquely into upper and lower section.
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E. Body cavities:
The cavities of the body house the internal organs, which commonly referred to as the viscera.
1. The Thoracic cavity:
It houses lungs and heart.
It is protected by the rib cage & associated musculature and the sternum anteriorly.
It consists of the right and left pleural cavities and mediastinum (the portion of tissues and
organs that separates the left and right lungs).
2. Abdomino - Pelvic Cavity:
It extends from the diaphragm inferior to the floor of the pelvis.
It is divided into superior abdominal cavity and inferior pelvic cavity by imaginary line passing
at upper pelvis.
a) Abdominal cavity: contains the stomach, intestine, liver, spleen and gallbladder.
b) Pelvic cavity: contains urinary bladder, rectum, and portions of the reproductive organs
3. Cranial cavity: contains the brain.
4. Spinal cavity (vertebral canal): contains the spinal cord.
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