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Introduction to A&P
Levels of Organization, Homeostasis, Body Cavities
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Anatomy – the study of internal and
external structures of the body, and the
physical relationships among body parts.
Ex. Studying the parts of the kidney.
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Physiology – the study of how living
organisms perform their vital functions.
Ex. Studying the mechanisms by which
the kidneys produce urine.
Terminology
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What 2 languages form the basis for most
anatomical and physiological words?
Biology
Embrology
Pathology
Histology
Cytology
Definitions
Definition: state of balance in which the
body’s internal environment remains in
the normal range. Our body is said to be
in homeostasis when the needs of its cells
are met and its activities are occurring
smoothly.
 Occurs with a balance of positive and
negative feedback.
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Homeostasis
Definition: sum total of all chemical
processes occurring in the body
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catabolism – breakdown of organic matter,
usually with the release of energy
anabolism – buildup of organic matter, usually
requiring the input of energy
Example: A catabolic process would be the
breakdown of a Carbohydrate for a release of
energy to the body. An anabolic reaction would
occur when that energy is captured and then
used (or required) for something else.
Metabolism

negative feedback – when the information
decreases the system’s output to bring
the system back to its set point
◦ Example: The level of glucose rises after a
meal, glucose stimulates the release of insulin,
and insulin encourages the passage of glucose
in the cells and therefore reduces the glucose
level.
+/- Feedback
positive feedback – the information
returned to the system increase the
deviation from the set point
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Example: Stimulating a nerve cell causes
sodium ions to flow across the membrane
into the cell; the sodium flow increases the
membrane’s passageways to encourage
more sodium ions to flow inward. The result
is a nerve impulse.
+/- Feedback
Anatomical Terms
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Anterior/ ventral –
Posterior / Dorsal –
Superior
Inferior
Medial
Lateral
Proximal
Distal
Body and
Dissection
Terms:
Superficial – At, near
or close to the
surface
Deep – Farther from
the body surface
Ex. - The thalamus
is located deep
within the brain.
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sagittal – lengthwise plane running from
front to back, it divides the body into
______ _____ ______sides
transverse – refers to a cut that divides
the body into _________ ____ ______
portions
Coronal (frontal) – lengthwise plane
running from side to side, it divides the
body into front _________ _____
___________ portions
Planes of the Body
Body Cavities
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The human is divided into an _____
portion (head, neck and trunk) and an
_____________ portion (upper and
lower limbs)
The _____ portion has 2 major cavities:
a ______ and a ventral cavity
Body Cavities
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dorsal – subdivided into the cranial (brain)
and spinal (vertebrae and spinal cord)
cavities
ventral (divided by the diaphragm) –
subdivided into the thoracic (heart, lungs,
esophagus) and abdominopelvic ( stomach,
intestines, spleen, liver, etc) cavities
Body Cavities
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thoracic – the
mediastinum separates
the thoracic cavity into
2 compartments, the
left and right lungs.
The mediastinum
includes the heart,
esophagus, trachea,
and thymus gland
abdominopelvic cavity
includes the upper
abdomen and the lower
pelvic areas. The
abdominal region is
subdivided into nine
regions
Body Cavities
 right
hypochondriac
 epigastric
 left
hypochondriac
 right lumbar
 umbilical
 left lumbar
 right iliac
 hypogastric
 left iliac region
Levels of Organization
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chemical level – lowest – chemicals
essential for maintaining life- atoms to
molecules to macromolecules to
organelles
cellular- basic structural and functional
unit; ex. Muscle and nerve cells
tissue- similar cells with same function;
ex. Connective tissue, epithelial tissue
Levels of Organization
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organ- structures of definite form and
function composed of 2 or more tissues;
ex. Heart, liver
system- association of organs with
common function ex. Digestive,
nervous
organism – all parts of the body
functioning with one another
Levels of Organization