Anatomy and Physiology
Introduction to Human Anatomy
and Physiology
Introduction
• The study of the human body probably
began with our earliest ancestors.
• Early healers relied heavily on
superstitions and magic.
• Over time, people began to believe that
humans could understand forces that
caused natural events; this developed into
modern science.
Anatomy and Physiology
• Anatomy is the branch of science that deals
with the structure (morphology) of body
parts—forms and organization.
• Physiology concerns the functions of body
parts—what they are and what they do.
• Body parts form a well-organized unit—the
human organism.
• A particular body part’s function depends on
its structure.
Levels of Organization in Living
Things
• Cellorganellestissuesorgans
organ systemsorganism
• Organelles—structures that carry on
specific activities; composed of
aggregates of large molecules
• Tissues—cells organized into layers or
masses that have common functions
Levels of Organization
continued:
• Organs—tissues form complex structures
with specialized functions
• Organ systems—groups of organs that
function closely together
• Organism—the entire group of organs
making up an individual
Levels of Organization
• Scientists recognize that all materials are
composed of chemicals.
• Hierarchy of all substances begins with
atoms, which join to form molecules,
which then combine into
macromolecules.
• Within the human organism, the basic
unit of structure and function is the cell.
Summary of Organization
• Body parts can be thought of as having
different levels of organization, such as
the atomic level, molecular level, or
cellular level.
• As you move from 1 level to the next,
complexity increases (cells are more
complicated than atoms).
Characteristics of Life
1.
2.
3.
4.
5.
Movement
Responsiveness
Growth
Reproduction
Respiration
6. Digestion
7. Absorption
8. Circulation
9. Assimilation
10. Excretion
Characteristics of Life Defined
• Movement—a self-initiated change in an
organism’s position or to motion of
internal parts.
• Responsiveness—an organism’s ability to
sense changes taking place inside or
outside its body and to react to these
changes
• Growth—an increase in body size
Characteristics of Life Defined
• Reproduction—process of making a new
individual
• Respiration—process of obtaining oxygen,
using oxygen to release energy from food, and
removing the resulting gaseous wastes
• Digestion—chemically and mechanically
breaks down food into simpler forms for
cellular use
Characteristics of Life Defined
• Absorption—the passage of substances through
certain membranes
• Circulation—movement of substances within
the body fluids
• Assimilation—the changing of absorbed
substances into chemically different forms
• Excretion—removal of wastes produced as a
result of body activities
Metabolism
• Each of the characteristics of life depends
upon physical and chemical changes that
occur within body parts.
• Taken together, these changes are called
metabolism.
Maintenance of Life
• The structures and function of almost all
body parts help maintain the life of the
organism.
• The only exceptions are an organism’s
reproductive structures, which ensure
that its species will continue into the
future.
Requirements to Maintain Life
1. Water is the most abundant chemical in the
body. It is required for many metabolic
processes, transports substances with the
body, and is important in regulating
temperature.
2. Foods are substances that provide the body
with the necessary nutrients—used as energy
sources, building materials, and to help
regulate vital chemical reactions.
Requirements continued:
3. Oxygen is used to release energy from food
which drives metabolic processes.
4. Heat energy is a product of metabolic
reactions. Generally, the more heat, the more
rapidly chemical reactions take place
(temperature is a measure of heat).
5. Pressure is an application of force to
something and is important in breathing.
Hydrostatic pressure produces blood
pressure.
Survival
• Although organisms require water, food,
oxygen, heat, and pressure, theses factors alone
are not enough to ensure survival.
• The quantities and the qualities of the factors
are also important.
• The amount of water entering and leaving an
organism must be regulated.
• Survival depends on the correct nutrients in
adequate amounts in an organism’s food.
Homeostasis
• As factors in an organism’s external
environment change, the conditions
within the organism (internal
environment) must remain relatively
stable in order for the organism to
survive.
• The maintenance of a stable internal
environment is called homeostasis.
The Set Point
• Like a thermostat, the body is adjusted to
an operating level called a set point.
• Body temperature in humans is regulated
by a homeostatic mechanism.
• A temperature-sensitive region in the
brain will trigger homeostatic
mechanisms to maintain a set point of
around 37o C.
Homeostasis in a Cold
Environment
• If the body temperature begins to drop, the brain
senses the change and triggers heat-generating
and heat-conserving activities.
• Small groups of muscles are stimulated to
contract involuntarily (shivering) which produces
heat to help warm the body.
• Also, blood vessels in the skin are signaled
to constrict so that less warm blood flows
through them; this retains heat in deeper
tissues.
Homeostasis in a Warm
Environment
• When a body becomes too hot, the brain’s
temperature control center triggers a series of
changes to promote loss of body heat.
• Sweat glands secrete perspiration; as water
evaporates from the surface, heat is carried
away and the skin is cooled.
• Blood vessels in the skin dilate,
allowing blood carrying heat to reach
the surface where it is lost to the
outside.
•
Other Homeostatic
Mechanisms
Pressure sensitive areas (receptors) in the walls
of blood vessels (arteries) sense changes in
blood pressure and signal a pressure control
center of the brain.
• If the pressure is above the set point, the brain
signals the heart, causing its chambers to
contract more slowly and with less force. Since
less blood enters the vessels, pressure decreases.
• If pressure is below the set point, the brain
signals the heart to contract more rapidly and
with greater force in order to raise pressure.
Feedback Mechanism
• Homeostasis is maintained by a self-regulating
control mechanism that receives signals or
feedback about changes away from the normal
set point.
• Since the changes away from the normal state
stimulate responses in the opposite direction,
the responses are called negative and the
control mechanism is called a negative
feedback process.
Normal Range
• Homeostatic mechanisms maintain a
relatively constant internal environment,
but individuals are different.
• Each individual has a normal value so the
concept of a normal range for the
population is clinically important.
Body Portions
•
The human
organism can be
divided into:
1. axial portion-includes the head,
neck, and trunk
2. appendicular
portion-- includes
the upper and lower
limbs.
Parts of the Axial Portion
• The axial portion has
2 major cavities: a
dorsal cavity and a
larger ventral cavity.
• The organs within a
cavity are called
visceral organs or
viscera.
Dorsal Cavity
• There are 2 parts to the dorsal cavity:
1. the cranial cavity, within the skull,
houses the brain
2. The vertebral canal, which contains the
spinal cord within sections of the
backbone (vertebrae)
Body Organization
Ventral Cavity
• The ventral cavity consists of
a thoracic cavity and an
abdominopelvic cavity.
• The thoracic cavity is
separated from the lower
abdominopelvic cavity by a
broad, thin muscle called the
diaphragm.
Thoracic Cavity
• The thoracic cavity wall is composed of
skin, skeletal (voluntary) muscles, and
various bones.
• A region called the mediastinum
separates the thoracic cavity into 2
compartments, which contain the right
and left lungs.
The Mediastinum
• The remaining
thoracic viscera—
heart, esophagus,
trachea, and
thymus gland—are
located with the
mediastinum.
Abdominopelvic Cavity
• The abdominopelvic cavity
includes an upper
abdominal portion and a
lower pelvic portion.
• It extends from the
diaphragm to the floor of
the pelvis.
• The viscera within the
abdominal cavity include
the stomach, liver, spleen,
gallbladder, kidneys, and
most of the small and
large intestines.
The Pelvic Cavity
• The pelvic cavity is the portion of the
abdominopelvic cavity enclosed by the
hip bones and contains the terminal
portion of the large intestine, the urinary
bladder, and the internal reproductive
organs.
Cavities Within the Head
1.
2.
3.
4.
Oral cavity—contains the
teeth and tongue.
Nasal cavity—located within
the nose; divided into right
and left portions by a nasal
septum; connected to airfilled sinuses
Orbital cavities—contain
eyes and associated skeletal
muscles and nerves.
Middle ear cavities—contain
the middle ear bones
Thoracic and Abdominopelvic
Membranes
• Parietal pleura—membrane lining the
walls of the right and left thoracic
compartments
• Visceral pleura—membrane covering the
lungs.
• (parietal refers to membrane attached to
the cavity wall; visceral refers to
membranes covering an organ)
Membranes Continued
• Parietal and visceral
pleural membranes are
separated by a thin
film of watery fluid
(serous fluid) that they
secrete. The potential
space between them is
called the pleural
cavity.
The Heart
• The heart is surrounded by
pericardial membranes.
• A thin visceral pericardium
covers the heart’s surface
and is separated from a
thicker parietal pericardium
by a small amount of fluid.
• The pericardial cavity is the
potential space between
these membranes.
Parietal Peritoneum
• In the abdominopelvic cavity, the lining
membranes are called peritoneal
membranes.
• A parietal peritoneum lines the wall, and
a visceral peritoneum covers each organ
in the abdominal cavity.
• The peritoneal cavity is the potential
space between these membranes.
Organ Systems
1. Integumentary
system
2. Skeletal system
3. Nervous system
4. Endocrine system
5. Cardiovascular
system
6. Lymphatic system
7. Digestive system
8. Respiratory system
9. Urinary system
10. Reproductive
system
Body Covering
• Organs of the integumentary system
include the skin and various accessory
organs, such as the hair, nails, sweat
glands, and sebaceous glands.
• These parts protect underlying tissues,
help regulate body temperature, house a
variety of sensory receptors, and
synthesize certain products.
Support
• The organs of the skeletal and
muscular systems support and
move body parts.
• The skeletal system consists of
bones, and ligaments and
cartilages which bind bones
together.
• The skeleton provides framework
and protective shields for soft
tissue, is attachment for muscles,
and stores inorganic salts.
Movement
• Muscles provide
forces that cause
body movements by
contracting and
pulling their ends
closer together.
• Muscles also
maintain posture and
are the main source
of body heat.
Integration and Coordination
• For the body to act as a unit, its parts
must be integrated and coordinated.
• The nervous system and endocrine
systems control and adjust various organ
functions, which maintains homeostasis.
Nervous System
• The nervous system
consists of the brain,
spinal cord, nerves, and
sense organs.
• Nerve cells within these
organs use
electrochemical signals
called nerve impulses to
communicate with one
another and with
muscles and glands.
Endocrine System
• The endocrine system includes all the glands that
secrete chemical messengers called hormones.
• The hormones move away from the glands in body
fluids, such as blood.
• Usually, a particular hormone affects only a particular
group of cells, or target tissue.
• The effect of a hormone is to alter the metabolism of
the target tissue.
• Organs of the endocrine system include the pituitary,
thyroid, parathyroid, and adrenal glands, as well as the
pancrease, ovaries, testes, pineal gland, and thymus
gland.
Cardiovascular System
• The cardiovascular system
includes the heart, arteries,
veins, capillaries, and blood.
• The heart is a muscular pump
that helps force blood through
the blood vessels.
• Blood transports gases,
nutrients, hormones, and
wastes. It carries O2 from the
lungs to all parts of the body.
Lymphatic System
• The lymphatic system is sometimes
considered part of the cardiovascular
system.
• It is composed of the lymphatic vessels,
lymph fluid, lymph nodes, thymus gland,
and spleen.
• This system transports some of the tissue
fluid back to the bloodstream and carries
certain fatty substances away from the
digestive organs.
• Cells of the lymphatic system are called
lymphocytes and they defend the body
against infection.
Digestive System
• The organs of the digestive system
receive foods from the outside. Then
they break down food molecules into
simpler forms that can pass through
cell membranes and be absorbed.
• The digestive system includes the
mouth, tongue, teeth, salivary glands,
pharynx, esophagus, stomach, liver,
gallbladder, pancreas, small intestine,
and large intestine.
Respiratory System
• The organs of the respiratory
system take air in and out and
exchange gases between the blood
and the air.
• Oxygen passes from air within the
lungs into the blood, and carbon
dioxide leaves the blood and enters
the lungs.
• The nasal cavity, pharynx, larynx,
trachea, bronchi, and lungs are
parts of this system.
Urinary System
• The urinary system consists of
the kidneys, ureters, urinary
bladder, and urethra.
• Kidneys remove wastes from
blood and help maintain the
body’s water and electrolyte
balance. The product of these
activities is urine.
Reproductive System
Reproduction is the process of producing
offspring (progeny).
• The male reproductive
system includes the
scrotum, testes,
epididymides, vasa
deferentia, seminal
vesicles, prostate gland,
bulbourethral glands,
penis, and urethra.
• These parts produce and
transfer sperm.
• The female reproductive
system consists of the
ovaries, uterine tubes,
uterus, vagina, clitoris,
and vulva.
• These organs produce
and maintain eggs and
support the development
of embryos and fetuses.
Reproductive Systems
– a
Anatomical Terminology
• Anatomical
position=body
standing erect,
face forward,
with upper
limbs at the
sides and with
the palms
forward.
Body Sections
1. Sagittal refers to a
lengthwise cut that divides
the body into left and right
portions.
2. Transverse refers to a cut
that divides the body into
superior and inferior
portions.
3. Coronal (frontal) refers to
a section that divides the
body into anterior and
posterior portions.