2nd Term Exam Notes – Principles of Health Science – Lepore – 2012-2013
Key Points
Homeostasis, Negative Feedback and Positive Feedback Mechanisms
I. Homeostasis is a state of equilibrium—or a “state” (-stasis) of “sameness” (homeo-)
A. The maintenance of a stable internal environment
B. Maintains the conditions necessary to support life
II. Homeostatic mechanisms operate at all levels of organization in the body, Including molecular,
cellular, tissues, organs, and systems.
III. There are hundreds of monitored events in the body that must be maintained in order for the body
to function efficiently.
These conditions are maintained by feedback mechanisms.
1. The vast majority of feedback mechanisms are negative feedback mechanisms.
a. A negative feedback mechanism tells the body to stop doing what is was doing when a monitored
event goes outside of its acceptable range.
Example: When under stress, the heart pumps harder and faster, increasing the heart rate. At rest, the
heart rate returns to a normal resting rate.
2. Very few feedback mechanisms are positive feedback mechanisms.
a. A positive feedback mechanism tells the body to continue doing what it has been doing.
Example: Blood platelets start to form a scab around a cut, and the process continues until the cut is
healed and no more platelets are needed.
Mechanisms to cool the body. (Negative Feedback)
1. Sweating
2. Blood vessel dilation
Mechanisms to warm the body. (Negative Feedback)
1. Shivering
a. Involuntary contractions of skeletal muscles to generate heat.
b. Constriction of dermal blood vessels (this slows passive heat loss)
Body Cavities, Body Planes and Directional Terms
Body cavities - openings within the torso which contain organs, protect delicate organs from accidental
shocks and bumps, and permit the expansion and contraction of organs without disrupting the activities
of other organs.
A. Dorsal cavity - located on the posterior/dorsal surface of the body and surrounds the brain and the
spinal cord.
1. Cranial Cavity - The bones of the skull create the cranial cavity to protect the brain.
2. Spinal (Vertebral) Cavity - formed by the vertebrae of the spine and surrounds the spinal cord.
B. Ventral Cavity - located on the anterior/ventral surface of the body which contains the chest and
abdomen. The walls are composed of skin, muscle, connective tissue, and bone, and the serous
membranes.
1. Thoracic Cavity - the portion of ventral cavity superior to the diaphragm.
a. Pleural Cavities - the spaces surrounding each lung.
b. Mediastinum - a broad middle tissue mass of the thoracic cavity; it encloses the heart and heart
vessels, as well as the esophagus.
c. Pericardial Cavity - space around which the heart is located, although it is filled with serious fluid as
well.
2. Abdominopelvic Cavity - the portion of the ventral cavity inferior to the diaphragm.
a. Abdominal Cavity - The superior portion of the abdominopelvic cavity. It extends from the diaphragm
to the superior margin of the pelvic girdle. The abdominal cavity contains the organs known as the
viscera which include the stomach, spleen, liver, gallbladder, pancreas, small intestine, and most of the
large intestine.
b. Pelvic Cavity - the pelvic cavity is surrounded by the pelvic bones. The pelvic cavity contains the
urinary bladder, cecum, appendix, sigmoid colon, rectum, and the male or female internal reproductive
organs.
Body planes - refer to any slice or cut through a three-dimensional structure allowing us to visualize
relationships between those parts. CT and MRI technology use these principles.
A. Sagittal: divides the body or organ vertically into right and left unequal parts: words used with the
sagittal plane include- medial, lateral, proximal and distal.
B. Midsagittal: divides the body or organ vertically into equal right and left parts
C. Frontal/ Coronal: a vertical plane dividing the body or an organ into anterior (front) and posterior
(back) sections.
D. Transverse: a horizontal plane dividing the body or an organ into superior (upper) and inferior (lower)
sections.
Body Directions
A. Superior – upper, or above something
B. Inferior – lower, or below something
C. Anterior or Ventral – front, in front of
D. Posterior – After, behind, following, toward the rear
E. Medial – Toward the mid-line, middle, away from the side
F. Lateral – toward the side of the body - away from the mid-line
G. Proximal – toward or near the trunk of the body, near the point
of attachment to the body
H. Distal – Away from, farther from the origin or attachment to the body
I. Dorsal: Near the upper surface, toward the back
J. Ventral: Toward the bottom, toward the belly
K. Cranial - refers to the head of the body
L. Caudal – means tail end
M. Internal – inside the body
Word Parts/Building Blocks – most medical terms are formed by a combination of basic word parts. An
understanding of how these parts work together makes interpreting medical language easier.
A. Prefixes – usually indicate location, time, or number and come at the beginning of a word
B. Suffixes – usually indicate the procedure, disease, or condition and come after the root word
C. Root Words – usually indicate the part of the body involved
D. Combining Vowel
1. usually “o”
2. attached to the root word
3. makes medical terms easier to pronounce
4. is NOT used a when suffix begins with a vowel
5. IS used when suffix begins with a consonant
Prefix Root Word Suffix + + = Medical Term
Common Medical Prefixes
a-, an- negative, without
ab- away from
ad- towards
anti- against
ante- before
bi- two, both
brachy- short
brady- slow
dys- painful, difficult
dors- back
endo- inside
epi- above, upon
hemi- half
hyper- excessive, above, more than
hypo- decrease, below, less
inter- between, among
intra- within, inside
macro- large, big
mal- bad
micro- small
neo- new
para- beside or below
peri- around
poly- many
post- after
sub- below
super- above
tachy- fast
Common Medical Suffixes
-algia painful
-asthenia weakness
-cele hernia
-centesis surgical puncture
-ectomy removal
-itis inflammation/infection
-gram picture
-malacia abnormal softening
-megaly enlargement
-necrosis death of tissue
-ology study of
-osis abnormal condition
-ostomy surgical opening
-otomy surgical incision
-orrhea flow
-pathy disease
-plasty surgical repair
-rrhaphy suture
-sclerosis abnormal hardening
-scope instrument to view
-stenosis narrowing
STUDY YOUR ROOT WORDS FROM THE CLASS HANDOUTS AND FROM THE PROJECT SHEET (the 78 terms
there as well)
Skeletal System
Divisions of skeleton
A. Axial skeleton
1. Skull
a. Cranium
b. Face
2. Vertebral column
3. Thorax
a. Ribs
b. Sternum
B. Appendicular skeleton
a. Upper extremities – shoulder girdle (scapula, clavicle), arms (radius, ulna, humerus), hands
(metacarpals, carpals, phalanges)
b. Lower extremities – hip girdle (pelvic bones), legs (femur, tibia, fibula, patella), and feet (tarsals,
metatarsals, phalanges)
Make sure to review your skeleton worksheets on the positions and names of ALL of those bones!