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Chapter 1 - Introduction to the Human Body
Objectives
1. Define anatomy and physiology, and name several sub-disciplines of
these sciences.
2. Describe the levels of structural organization that make up the human
body.
3. Define the eleven systems of the human body, the organs present in
each, and their general functions.
4. Define the important life processes of the human body.
5. Describe the components of a feedback system.
6. Contrast the operation of negative and positive feedback systems.
7. Describe the orientation of the body in the anatomical position.
8. Relate the common names to the corresponding anatomical descrip-
tive terms for various regions of the human body.
9. Define the anatomical planes and sections and the directional terms
used to describe the human body.
10. Describe the principal body cavities, the organs they contain, and their
associated linings.
11. Name and describe the nine abdominopelvic regions and the four
abdominopelvic quadrants.

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I. A & P defined
Anatomy = study of structures by dissection, imaging, and microscopy
• macro - gross & systemic, embryology & development
• micro - cytology, histology
Physiology = study of functions by chemical and physical means
cells
organs
systems
[Pathology = study of anatomy and physiology during illness or after
death]
II. Levels of Organization
chemicals → cells → tissues → organs → systems
(epithelial, (contain (accomplish
muscle, several a complete
connective, types of function)
nervous) tissues)
1. A cell is the basic unit of life in which functional substances and
parts are dissolved or suspended in fluid cytosol, and surrounded
by functional membranes made of lipids and proteins.
2. A tissue is an organized group of cells of different types as well as
their extracellular material (called matrix)
there are only 4 classes of tissue :
• epithelial tissue covers surfaces (e.g., skin, lining of body
cavities, lining of hollow organs like bladder, stomach)
• muscle tissue performs work or alters the shape of an
organ
• nervous tissue includes neurons and their support cells
(called neuroglia)
• connective tissue is all the rest (e.g., blood cells, bone
& cartilage cells) cells & matrix that fill body spaces and
bind tissues together

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3. An organ is composed of several tissues that accomplish a specific
function
ex: stomach is lined with specialized epithelium,
surrounded by connective tissue that contains blood vessels
and nerves,
surrounded by 3 layers of smooth muscle,
covered with another layer of epithelium and connective
tissue that holds it in place.
Working together, the tissues accomplish the function of
grinding, dissolving, and partially digesting food.
4. A system is composed of several organs.
ex: the digestive system includes the mouth (chew and moisten
food), esophagus (deliver food to stomach), stomach (grind
and dissolve food), small intestine (finishes digesting food
and absorbs nutrients), large intestine (reabsorbs water to
prevent loss), and rectum (stores feces).
5. An organism is one unit of life.
ex: Homo sapiens, Canis familiaris, Saccharomyces cerviseae

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Systems
1. Integument = skin, linings, hair, nails, sweat/oil glands
fx: -barrier between environment & internal tissues/organs
- interacts with environment (temp regulation, H2O & waste secretion)
- performs one of the steps in synthesis of vitamin D
2. Skeletal = bones, joints & cartilage
fx: - support and provide fulcrum for movement
- calcium reservoir
- generates blood cells
3. Muscular = skeletal, cardiac, smooth
fx: - movement & posture
- generates body heat
4. Nervous = brain, spinal cord, peripheral nerves, sense organs
fx: - monitors internal & external environment, and generates appropriate responses
- communicates by means of action potentials (electrical)
5. Endocrine = organs & tissues that produce hormones
fx: - monitors internal environment, and acts on other organs/tissues to produce
appropriate response
- communicates through blood using chemical reactions on the target organ
6. Cardiovascular = heart, vessels, blood (plasma)
fx: - distributes nutrients (including O2)
- delivers wastes for removal (including CO2)
- prevents excessive bleeding
- regulates pH and temperature
7. Lymphatic & Immune = lymph fluid, lymph vessels, organs which generate & modify
lymphocytes
fx: - transports fluids & nutrients
- participates in production, maturation & specificity of immune cells
- produces antibodies & cytokines
8. Respiratory = lungs & associated passageways (bronchi, trachea, pharynx)
fx: - transports gases (O2, CO2, H2O-vapor)
- regulates pH and temperature
- produces vocal sounds
9. Digestive = GI tract (esophagus, stomach, small & large intestines), and associated organs
(salivary glands, liver & gall bladder, pancreas)
fx: - prepares ingested food for absorption
- eliminates external solid wastes
- produces hormones
10. Urinary = kidneys, ureters, bladder, urethra
fx: - eliminates internal, soluble wastes
- regulates pH and water balance
- produces hormones
11. Reproductive = organs (ovary, testis) that produce gametes, & accessory organs (Fallopian
tubes, uterus, epididymis, vas deferens, penis)
fx:- produces gametes
- produces hormones
- houses & nourishes fetus

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III. Life is recognized by certain characteristics:
• Metabolism: the sum of chemical processes in an organism
Anabolism = chemical reactions that build-up or synthesize
Catabolism = chemical reactions that break-down or fragment
Equilibrium exists when the organism is in "steady state", i.e.,
amount of anabolism equals amount of catabolism.
ex: healthy adult is in steady state
ex: growing healthy child is in anabolic state
• Responsiveness: ability to detect and respond to external stimuli
ex: afferent nervous system monitors external environment, and
then the efferent nervous system alters the body to accommo-
date the environment.
• Movement: displacement of the whole organism as well as rear-
rangement of the relative positions of the organism's parts
ex: skeletal muscle impels legs to run
ex: smooth muscle causes intestine to move food along.
• Growth: increase in organism size (may be cyclical as in bacteria)
caused when anabolism exceeds catabolism.
• Differentiation is mostly present in multicellular organisms. Dif-
ferent cells or tissues or organs specialize to perform one function
and lose the ability to perform any other function.
ex: lymphocytes in the blood detect and respond to foreign
materials in the body (e.g., bacteria); they are not able to carry
oxygen or phagocytose debris or cause the blood to clot.
• Reproduction: forming new cells to replace damaged or senescent
cells or even to "replace" the whole organism.
ex: sperm and ova can result in a baby;
ex: "stem cells" in your epidermis can reproduce to replace the
damaged epithelium when you injure your skin

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IV. Homeostasis is the normal, healthy, adult state = equilibrium
A major mechanism for homeostasis is communication and exchange
of materials between intracellular fluid (ICF), interstitial fluid
(between cells) and plasma (the liquid portion of blood).
(Extracellular fluid (ECF) = plasma plus interstitial fluid.)
1. A major mechanism for homeostasis is "negative feedback"
Negative Feedback: a specific stimulus causes a specific
response, and the response "fixes" (i.e., reverses) the stimulus.
Stimulus and response mechanisms are commonly
hormones and nerves
ex: stimulus is scary situation,
response is secretion of hormone adrenalin which sends blood
and oxygen to heart, lungs, and muscles so you can escape,
result is decrease in adrenalin due to escape from the original
stimulus; blood and O2 transport return to resting state
ex: sensors in the tendons of your legs detect stretching
when you are about to lose your balance,
reflex neuron causes contraction of the muscle attached to the
tendon,
muscle pulls you upright & releases the stretch stimulus,
result is restoration of balance
2. Positive feedback: specific stimulus causes a specific response
that makes the stimulus even stronger → even stronger response….
note: this can be a vicious circle unless something else
("termination mechanism") intervenes.
ex: stretching of cervix during childbirth stimulates secretion of
hormone (oxytocin) which causes uterus to contract and stretch
the cervix even more, etc.
Here the "termination mechanism" is baby's birth which inter-
rupts the feedback by eliminating the source of cervical
stretching.

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3. Feedback systems always involve 3 components:
receptor - senses the stimulus
control center - interprets the stimulus & determines response
effector - produces the response
If any of the 3 components is missing or malfunctions, then the
feedback system won't work.
ex: Site in the hypothalamus of the brain is responsible for
keeping the body at 37o
C (98.6o
F) by regulating heat loss
through the skin, breath, etc.
When bacterial toxins are released into the body, chemicals
called prostaglandins are produced which cause the hypothala-
mus to set the equilibrium temp at a higher value.
∴ bacterial infections cause fever (“failure” of temperature
equilibrium).
V. Anatomical Terms (See Fig 1.5)
"Anatomical Position" =standing, facing observer, palms forward., feet flat
prone = face down
supine = face up
Major body sections:
head cephalic
neck cervical
trunk thoracic
abdominal
pelvic
arm brachial
wrist/hand carpal
leg femoral
crural
ankle/foot tarsal
Anatomic Directions:
below/above inferior/superior caudal/cephalic
nearest/farthest proximal/distal
front/rear anterior/posterior ventral/dorsal
central/side medial/lateral

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Dissection planes
sagittal divides right from left
coronal = frontal divides front from rear
transverse divides superior from inferior
Divisions of abdominal-pelvic cavity:
RUQ, LUQ, RLQ, LLQ are divided by sagittal & transverse planes
through umbilicus.
Alternative nomenclature:
R & L hypochondriac areas are lateral to epigastric area
R & L lumbar areas are lateral to umbilical area
R & L iliac (inguinal) areas are lateral to hypogastric (pubic)
area (see Fig 1.12)

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VI. Body Cavities
Dorsal (rear) cavity contains cranial cavity (brain)
vertebral canal (spinal column)
Ventral (front) cavity is filled with visceral organs and lined by serous or
mucous membranes (serous = closed cavity; mucous = open cavity)
superior portion = thoracic cavity separated by
inferior portion = abdominal-pelvic cavity diaphragm
thoracic cavity contains:
2 pleural cavities - contain lungs; lined by pleural membranes
mediastinal space -contains trachea, esophagus, blood vessels &
lymph vessels
pericardial cavity –contains heart; lined by pericardial membranes
abdominal-pelvic cavity lined by peritoneal membrane:
abdominal cavity contains
spleen,
pancreas,
liver,
gall bladder, everything above
stomach, the pelvic rim
small intestine,
proximal part of large intestine.
pelvic cavity contains
distal part of large intestine (sigmoid colon & rectum),
gonads and accessory reproductive organs,
bladder (note: kidneys are in abdominal cavity)