Glossary
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Epizootic
A diffuse, rapidly spreading outbreak of a
disease affecting many animals in any region at the
same time, often with the implication that it may
extend to humans, such as bird flu.
Erectile
Capable of being erected or raised to an erect
position.
Erythema
The redness or inflammation of the skin or
mucous membranes produced by the congestion of
superficial capillaries. (Adjective: erythematous)
Etiology
The study or theory of all factors that may
be involved in the development of a disease, includ-
ing susceptibility of an individual, the nature of the
disease agent, and the way in which an individual’s
body is invaded by the agent; or the cause of a
disease.
Eukaryotic
Pertaining to an organism with cells having
a true nucleus; that is, a highly complex, organized
nucleus surrounded by a nuclear membrane contain-
ing organelles and exhibiting mitosis.
Euploid
Pertaining to an individual, organism, strain,
or cell with a balanced set or sets of chromosomes,
in any number, that is an exact multiple of the nor-
mal, basic haploid number characteristic of the spe-
cies; or such an individual, organism, strain, or cell.
Evisceration
The removal of the viscera from the
abdominal cavity, or disembowelment; or the extru-
sion of an internal organ through a wound or surgi-
cal incision.
Exacerbation
An increase in the severity of a disease
as marked by greater intensity in any of its signs and
symptoms.
Exfoliation
Peeling and sloughing off of tissue cells in
scales or layers. (Adjective: exfoliative)
Exocytosis
The discharge of cell particles, which are
packaged in membrane-bound vesicles, by fusion of
the vesicular membrane with the plasma membrane
and subsequent release of the particles to the exterior
of the cell.
Exogenous
Developed or originating outside the body,
as a disease caused by a bacterial or viral agent
foreign to the body.
Exophthalmos
A marked or abnormal protrusion of
the eyeball.
Extension
A movement that allows the two elements
of any jointed part to be drawn apart, increasing the
angle between them, as extending the leg increases
the angle between the femur and the tibia.
Extrapyramidal
Pertaining to motor systems supplied
by fibers outside the corticospinal or pyramidal tracts.
Extravasation
A discharge or escape, usually of blood,
serum, or lymph, from a vessel into the tissues.
Extubation
The process of withdrawing a previously
inserted tube from an orifice or cavity of the body.
Exudate
Fluid, cells, or other substances that have
been slowly exuded or have escaped from blood ves-
sels and have been deposited in tissues or on tissue
surfaces. (Adjective: exudation)
Fascia
A sheet or band of fibrous connective tissue that
may be separated from other specifically organized
structures, such as the tendons, aponeuroses, and
ligaments.
Febrile
Pertaining to or characterized by an elevated
body temperature, or fever.
Fibrillation
A small, local, involuntary contraction of
muscle resulting from spontaneous activation of a
single muscle fiber or of an isolated bundle of nerve
fibers.
Fibrin
A stringy, insoluble protein formed by the
action of thrombin on fibrinogen during the clotting
process.
Fibrosis
The formation of fibrous connective tissue,
as in the repair or replacement of parenchymatous
elements.
Filtration
The process of passing a liquid through or as
if through a filter, which is accomplished by gravity,
pressure, or vacuum.
Fimbria
Any structure that forms a fringe, border, or
edge or the processes that resemble such a structure.
Fissure
A cleft or a groove, normal or otherwise, on
the surface of an organ or a bony structure.
Fistula
An abnormal passage or communication from
an internal organ to the body surface or between
two internal organs.
Flaccid
Weak, soft, and lax; lacking normal muscle
tone.
Flatus
Air or gas in the intestinal tract that is expelled
through the anus. (Adjective: flatulent)
Flexion
A movement that allows the two elements of
any jointed part to be brought together, decreasing
the angle between them, as bending the elbow.
Flora
The microorganisms, such as bacteria and fungi,
both normally occurring and pathologic, inhabiting
the external or internal surfaces of the body.
Focal
Relating to, having, or occupying a focus.
Follicle
A sac or pouchlike depression or cavity.
Fontanel
A membrane-covered opening in or between
bones, such as the soft spot covered by tough mem-
branes between the bones of an infant’s incompletely
ossified skull.
Foramen
A natural opening or aperture in a membra-
nous structure or bone.
Fossa
A hollow or depressed area, especially on the
surface of the end of a bone.
Fovea
A small pit or depression in the surface of a
structure or organ.
Fundus
The base or bottom of an organ or the portion
farthest from the mouth of an organ.
Ganglion
One of the nerve cell bodies, chiefly collected
in groups outside the central nervous system. (Plural:
ganglia)
Genotype
The entire genetic constitution of an indi-
vidual, as determined by the particular combination
and location of the genes on the chromosomes; or
the alleles present at one or more sites on homolo-
gous chromosomes.
Glia
The neuroglia, or supporting structure of nervous
tissue.
Globulin
One of a broad group of proteins classified
by solubility, electrophoretic mobility, and size.
Gluconeogenesis
The formation of glucose from
any of the substances of glycolysis other than
carbohydrates.
