717
acidity
concentration of free, unbound
hydrogen ion in a solution; the higher the H
+
concentration, the greater the acidity
acidosis
(ass-ih-DOH-sis) any situation in
which arterial H
+
concentration is elevated
above normal resting levels;
see also
metabolic
acidosis, respiratory acidosis
acquired refl
ex
behaviors that appear to be
stereotypical and automatic, but which in fact
result from considerable conscious effort to be
learned (also called
learned refl
ex
)
acrosome
(AK-roh-sohm) cytoplasmic vesicle
containing digestive enzymes and located at
head of a sperm
acute phase response
responses of tissues and
organs distant from site of infection or immune
response
adaptation
(evolution) a biological characteristic
that favors survival in a particular environment;
(neural) decrease in action potential frequency
in a neuron despite constant stimulus
adenine
one of the four bases making up DNA;
also a breakdown product of ATP used as a
neurotransmitter
adenoid
lymphoid tissue; also known as
pharyngeal tonsil
adenosine diphosphate (ADP)
(ah-DEN-oh-
seen dy-FOS-fate) two-phosphate product of
ATP breakdown
aerobic
(air OH bik) in presence of oxygen
afferent
(AF-er-ent) carrying toward
afferent arteriole
vessel in kidney that carries
blood from artery to renal corpuscle
afferent division (PNS)
neurons in the
peripheral nervous system that project to the
central nervous system
afferent neuron
neuron that carries information
from sensory receptors at its peripheral endings
to CNS; cell body lies outside CNS
afferent pathway
component of refl ex arc
that transmits information from receptor to
integrating center
affi
nity
strength with which ligand binds to its
binding site
Glossary
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