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Body Structure and Function
- an overview
Introduction to Body Structure & Function
(Anatomy & Physiology)
Boone County ATC
Laura M Williams
Spring 2015
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Cells, Tissues, and Organs
• The basic unit of body
structure is the cell.
• Parts of a cell
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Chromosomes and Mitosis
• Chromosomes are thread-like structures in the nucleus
that contain genes.
• Each cell has 46 chromosomes.
• Genes control the traits children inherit from their parents.
• The process of cell division is mitosis.
• The nucleus controls cell reproduction.
• Cells reproduce by dividing in half.
• Mitosis is needed for tissue growth and repair.
• During mitosis, the 46 chromosomes arrange themselves in 23
pairs. As the cell divides, the 23 pairs are pulled in half. The two
new cells are identical.
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Tissues
• Groups of cells with similar functions combine to form
tissues.
• Epithelial tissue
• Connective tissue
• Muscle tissue
• Nerve tissue
• Groups of tissue with the same function form organs.
• Organs have one or more functions.
• Systems are formed by organs that work together to
perform special functions.
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The Integumentary System
• The integumentary system,
or skin, is the largest
system.
• There are two skin layers.
• The epidermis
• The dermis
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Skin’s Function
• The skin has many functions.
• It is the body’s protective covering.
• It prevents microorganisms and other substances from entering
the body.
• It prevents excess amounts of water from leaving the body.
• It protects organs from injury.
• Nerve endings in the skin sense both pleasant and unpleasant
stimulation.
• It helps regulate body temperature.
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6
The Musculoskeletal System
• The musculoskeletal system:
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•
•
Provides the framework for the body
Lets the body move
Protects and gives the body shape
• Bones
•
There are four types of bones:
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•
•
•
•
Long bones bear the body’s weight.
Short bones allow skill and ease in movement.
Flat bones protect the organs.
Irregular bones are the vertebrae in the spinal column.
Bones contain bone marrow inside their hollow centers.
•
Blood cells are formed in the bone marrow.
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Joints
• Joints
• A joint is the point at which
two or more bones meet.
• Joints allow movement.
• There are three types of
joints.
• Ball-and-socket joint allows
movement in all directions.
• Hinge joint allows movement
in one direction.
• Pivot joint allows turning
from side to side.
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Muscles
• Voluntary and involuntary muscles
• Voluntary muscles can be consciously controlled.
• Involuntary muscles work automatically.
• Cardiac muscle is in the heart.
• It is an involuntary muscle.
• Muscles have three functions.
• Movement of body parts
• Maintenance of posture
• Production of body heat
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The Nervous System
• The nervous system controls, directs, and coordinates body
functions.
• It has two main divisions: the central nervous system and the
peripheral nervous system.
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Divisions of the Nervous System
● The central nervous system (CNS) consists of the brain and spinal
cord.
 The brain is covered by the skull.
 The spinal cord lies within the spinal column. It contains pathways that
conduct messages to and from the brain.
● The peripheral nervous system has 12 pairs of cranial nerves and 31
pairs of spinal nerves.
 Some peripheral nerves form the autonomic nervous system.
 The autonomic nervous system is divided into the sympathetic nervous
system and the parasympathetic nervous system.
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Central Nervous System
• The three main parts of the
brain are:
• The cerebrum
• The cerebellum
• The brainstem
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Cerebral Structure and Function
• Cerebrum
• The largest part of the brain
• The center of thought and intelligence
• Divided into two halves called the right and left hemispheres. The
right hemisphere controls movement and activities on the body’s
left side. The left hemisphere controls the right side.

Cerebral cortex
•
•
The outside of the cerebrum
Controls the highest brain functions
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Cerebral Structure and Function (Cont’d)

Cerebellum
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Regulates and coordinates body movements
Controls balance and the smooth movements of
voluntary muscles
Brainstem
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
Connects the cerebrum to the spinal cord
Contains the midbrain, pons, and medulla.
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Peripheral Nervous System
• Contains cranial nerves and spinal nerves
• Cranial nerves conduct impulses between the brain and the
head, neck, chest, and abdomen.
• Spinal nerves carry impulses from the skin, extremities, and the
internal structures not supplied by cranial nerves.
• Some peripheral nerves form the autonomic nervous system.
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The Autonomic Nervous System
● Controls involuntary muscles and certain body
functions that occur automatically.
● Divided into the sympathetic nervous system and
the parasympathetic nervous system.
 The sympathetic nervous system speeds up functions.
 The parasympathetic nervous system slows functions.
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Sensory Organs
• The sense organs
• The five senses are sight, hearing, taste, smell, and touch.
• Receptors for taste are in the tongue (taste buds).
• Receptors for smell are in the nose.
• Touch receptors are in the dermis, especially in the toes and fingertips.
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The Eye
• The eye has three layers:
• The sclera, the white of the
eye, is the outer layer.
• The choroid is the second layer.
•
Blood vessels, the ciliary
muscle, and the iris make up
the choroid.
• The retina is the inner layer.
•
It has receptors for vision
and the nerve fibers of the
optic nerve.
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The Ear
• The ear functions in
hearing and balance.
• It has three parts.
• External ear
• Middle ear
• Inner ear
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The Circulatory System
• The circulatory system is made up of the blood, heart, and
blood vessels.
• The circulatory system has many functions.
•
•
•
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Blood carries food, oxygen, and other substances to the cells.
Blood removes waste products from cells.
Blood and blood vessels help regulate body temperature.
The system produces and carries cells that defend the body from
microbes that cause disease.
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Blood Structure and Function
•
Blood
•
•
•
•
The blood consists of blood cells and plasma.
Red blood cells (RBCs) are called erythrocytes.
White blood cells (WBCs) are called leukocytes.
Platelets (thrombocytes) are needed for blood clotting.
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Cardiac Structure and Function
• The heart:
• Is a muscle
• Pumps blood through the blood vessels to the tissues and cells
• Lies in the middle to lower part of the chest cavity toward the left
side
• The heart is hollow and has three layers.
• The pericardium is the outer layer.
• The myocardium is the second layer.
• The endocardium is the inner layer.
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Cardiac Structure and Function (Cont’d)
• The heart has four chambers.
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The right atrium receives blood from body tissues.
The left atrium receives blood from the lungs.
The right ventricle pumps blood to the lungs for oxygen.
The left ventricle pumps blood to all parts of the body.
Valves between the atria and ventricles allow blood flow in one
direction.
• Heart action has two phases.
• Diastole is the resting phase.
• Systole is the working phase.
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The Vascular System
• Blood vessels
• Blood flows to body tissues and cells through the blood vessels.
• There are three groups of blood vessels: arteries, capillaries, and
veins.
• Arteries carry blood away from the heart.
• Capillaries connect to arterioles and venules.
• Veins carry waste products back to the heart.
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The Respiratory System
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The respiratory system brings
oxygen into the lungs and removes
carbon dioxide.
Oxygen is needed to live.
Respiration is the process of
supplying the cells with oxygen
and removing carbon dioxide from
them.
Respiration involves inhalation
(inspiration) and exhalation
(expiration).
The lungs are spongy tissues. Each
lung is divided into lobes.
Each lung is covered by a twolayered sac called the pleura.
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Respiratory System
Structure and Function
• The lungs are filled with alveoli, blood vessels, and nerves.
• The lungs are separated from the abdominal cavity by the diaphragm.
• Each lung is covered by a two-layered sac called the pleura.
• A bony framework made up of the ribs, sternum, and vertebrae protects
the lungs.
• Air enters the body through the nose. The air then passes into the
pharynx (throat) and then into the larynx (voice box).
• A piece of cartilage, the epiglottis, acts like a lid over the larynx. The
epiglottis prevents food from entering the airway during swallowing.
During inhalation the epiglottis lifts up to let air pass over the larynx.
Air passes from the larynx into the trachea (windpipe).
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The Digestive System (Gastrointestinal
System)
•
•
•
The digestive system’s major
parts are the mouth,
pharynx, esophagus,
stomach, small intestine, and
large intestine.
Digestion is the process of
physically and chemically
breaking down food so that it
can be absorbed for use by
the cells.
Digestion begins in the
mouth.
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Digestion and Elimination
• The digestive system:
•
Breaks down food physically and chemically so it can be absorbed
for use by the cells (digestion)
•
Removes solid wastes from the body
• The digestive system involves the alimentary canal (GI
tract) and the accessory organs of digestion.
•
The alimentary canal extends from the mouth to the anus.
•
Accessory organs are the teeth, tongue, salivary glands, liver,
gallbladder, and pancreas.
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The Urinary System
• Removes waste products
from the blood
• Maintains water balance
within the body
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The Urinary System (Cont’d)
• The kidneys:
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•
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Are two bean-shaped organs in the upper abdomen
Are protected by the lower edge of the rib cage
Each kidney has more than a million tiny nephrons.
Each nephron is the basic working unit of the kidney.
The ureters carry urine from the kidneys to the bladder.
Urine is stored in the bladder until the need to urinate is felt.
Urine passes from the bladder through the urethra.
Urine passes from the body through the meatus (the opening at
the end of the urethra).
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The Reproductive System
• Human reproduction results from the union of a male sex cell
and a female sex cell.
• The differences in the male and female reproductive systems
allow for the process of reproduction.
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The Male Reproductive System
• The testes (testicles) are the
male sex glands (gonads).
• Male sex cells (sperm) are
produced in the testes.
• Testosterone, the male hormone,
is produced in the testes. This
hormone is needed for
reproductive organ function.
• Semen is a fluid that carries
sperm from the male
reproductive tract.
• Sperm travel to the epididymis
through the vas deferens to the
urethra.
• Each vas deferens joins a seminal
vesicle.
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The Female Reproductive System
●
●
The two female gonads are
called ovaries. An ovary is on
each side of the uterus in the
abdominal cavity. The ovaries
contain ova or eggs. Ova are
the female sex cells. One ovum
(egg) is released monthly
during the woman’s
reproductive years. Release of
an ovum is called ovulation.
The ovaries secrete the female
hormones estrogen and
progesterone for reproductive
system function.
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The Female Reproductive System (Cont’d)
• The external female genitalia are called the vulva:
• The mons pubis is a rounded, fatty pad over a bone called the
symphysis pubis. The mons pubis is covered with hair in the adult
female.
• The labia majora and labia minora are two folds of tissue on each
side of the vaginal opening.
• The clitoris is a small organ composed of erectile tissue. It becomes
hard when sexually stimulated.
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Female Reproductive System
• Menstruation
• If pregnancy does not occur, the endometrium breaks up and is
discharged from the body.
• Ovulation
• Release of a mature ovum
• Fertilization
• To reproduce, a male sex cell (sperm) must unite with a female sex
cell (ovum).
• The uniting of the sperm and ovum into one cell is called
fertilization.
• The fertilized cell travels down the fallopian tube to the uterus.
• The fertilized cell implants in the thick endometrium and grows
during pregnancy.
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The Endocrine System
• The endocrine system is made up of glands called the endocrine
glands.
• The endocrine glands secrete chemical substances called
hormones into the bloodstream.
• Hormones regulate the activities of other organs and glands in the
body.
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The Pituitary Gland
• The pituitary gland is called the master gland.
• It is at the base of the brain behind the eyes.
• The anterior pituitary lobe secretes:
•
•
•
•
Growth hormone (GH)
Thyroid-stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Hormones that regulate growth, development, and function of the
male and female reproductive systems
• The posterior pituitary lobe secretes:
• Antidiuretic hormone (ADH)
• Oxytocin
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Thyroid and Parathyroid Glands
• The thyroid gland is in the neck in front of the larynx.
• The thyroid gland secretes thyroid hormone (TH, thyroxin).
• Thyroid hormone regulates metabolism.
• The four parathyroid glands secrete parathormone.
• Two lie on each side of the thyroid gland.
• Parathormone regulates calcium use.
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Adrenal Glands
• There are two adrenal glands.
• One is on the top of each kidney.
• The adrenal medulla secretes epinephrine and norepinephrine.
• The adrenal cortex secretes:
• Glucocorticoids
• Mineralocorticoids
• Small amounts of male and female sex hormones
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Pancreas and Gonads
• The pancreas secretes insulin.
• Insulin regulates the amount of sugar in the blood available for use
by the cells.
• The gonads are the glands of human reproduction.
• Male sex glands (testes) secrete testosterone.
• Female sex glands (ovaries) secrete estrogen and progesterone.
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The Immune System
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•
•
•
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Protects the body from disease and infection
Defends against threats inside and outside the body
Gives the body immunity
Antigens are substances that cause an immune response.
Special cells and substances function to produce
immunity:
•
•
•
•
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Antibodies
Phagocytes
Lymphocytes
B lymphocytes (B cells)
T lymphocytes (T cells)
• Killer T cells
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Immune System Response
•
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


Antibodies—normal body substances that recognize other substances. They
are involved in destroying abnormal or unwanted substances. Antibodies
recognize and bind with unwanted antigens. This leads to the destruction of
unwanted substances and the production of more antibodies.
Phagocytes—white blood cells that digest and destroy microorganisms and
other unwanted substances.
Lymphocytes—white blood cells that produce antibodies. Lymphocyte
production increases as the body responds to an infection.
B lymphocytes (B cells)—cause the production of antibodies that circulate in
the plasma. The antibodies react to specific antigens.
T lymphocytes (T cells)—cells that destroy invading cells. Killer T cells produce
poisons near the invading cells. Some T cells attract other cells. The other
cells destroy the invaders.
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Quality of Life
• Basic knowledge of the body’s normal structure and function:
• Should result in safe, quality care
• Will help you better understand the reasons for the care you give
• Always treat the person and the person’s body with dignity and
respect.
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