969
GLOSSARY
additional similar changes, producing
unstable conditions. p. 539
posterior
(pos-te
¯r
e-or)
Toward the
back; opposite of anterior. p. 21
postganglionic f
ber
(po
¯st
gang-gle-on
ik
F
ber)
Autonomic nerve F
ber on
the distal side of a ganglion. p. 424
postnatal
(po
¯st-na
tal)
After birth. p. 875
postsynaptic neuron
(po
¯st
sı˘-nap
tik
nu
ron)
One of two adjacent
neurons transmitting an impulse;
cell on the “receiving” side of a
synapse. p. 365
postsynaptic potential
(po
¯st
sı˘-
nap
tik po-ten
shal)
Membrane
polarization is increased (excitatory)
or decreased (inhibitory) in the
postsynaptic neuron with repeated
stimulation over an excitatory
or inhibitory pathway so that
the neuron will either F
re or not
respond. p. 371
preganglionic f
ber
(pre
gang-gle-on
ik
F
ber)
Autonomic nerve F
ber
located on the proximal side of a
ganglion. p. 424
pregnancy
(preg
nan-se)
Condition in
which a female has a developing
offspring in her uterus. p. 876
preload
(pre
lo
¯d)
Blood entering and
F lling the relaxed ventricles prior to
their contraction p. 586
prenatal
(pre-na
tal)
Before birth. p. 876
presbyopia
(pres
be-o
pe-ah)
Loss of
the eye
s ability to accommodate due
to declining elasticity in the lens;
farsightedness of age. p. 472
presynaptic neuron
(pre
sı˘-nap
tik
nu
ron)
One of two adjacent
neurons transmitting an impulse;
cell on the “sending” side of a
synapse. p. 365
primary germ layers
(pri
ma-re jerm
la
¯
erz)
Three layers (endoderm,
mesoderm, and ectoderm) of cells
in the embryo that divide and
differentiate into speciF
c tissues and
organs. p. 885
primary immune response
(pri
ma-re
ı˘-mu
¯n
re-spons
)
Immune system
s
response to an initial encounter with
a nonself antigen. p. 637
primary sex organs
(pri
ma-re seks
or
ganz)
Sex cell-producing parts;
testes in males and ovaries in
females. p. 833
prime mover
(prı¯m moo-v
er)
Muscle
that provides a particular body
movement. p. 304
primordial Follicle
(pri-mor
de-al fol
lı˘-kl)
Egg enclosed by a single layer of
cells in the ovary. p. 847
product
(prod
ukt)
The result of a
chemical reaction. p. 58
platelet
(pla
¯t
let)
Cytoplasmic fragment
formed in the bone marrow that
helps blood clot. p. 162
pleiotropy
(ple
¯
o-tro-pe
¯)
Gene that has
several expressions (phenotypes).
p. 924
pleural
(ploo
ral)
Pertaining to the
pleura or membranes surrounding
the lungs. p. 12
pleural cavity
(ploo
ral kav
ı˘-te)
Potential space between pleural
membranes. p. 12
pleural membrane
(ploo
ral mem
bra
¯n)
Serous membrane that encloses the
lungs and lines the chest wall. p. 12
plexus
(plek
sus)
Network of interlaced
nerves or blood vessels. p. 420
pluripotent
(ploo-rip
o-tent)
Cell able
to differentiate to yield several
specialized cell types. p. 106
PNS
Peripheral nervous system. p. 354
polar body
(po
lar bod
e)
Small,
nonfunctional cell that is a product
of meiosis in the female. p. 849
polarization
(po
lar-ı˘-za
shun)
Electrical charge on a cell membrane
surface due to an unequal distribution
of positive and negative ions on either
side of the membrane. p. 365
polar molecule
(po
lar mol
e
˘-ku
¯l)
Combination of atoms in which the
electrical charge is not distributed
symmetrically. p. 57
polygenic
(pol
e
˘-je
¯n
ik)
An inherited
trait that results from the actions of
more than one gene. p. 924
polymorphonuclear leukocyte
(pol
e-
mor
fo-nu
kle-ar lu
ko-sı¯t)
White
blood cell with an irregularly lobed
nucleus; neutrophil. p. 531
polynucleotide
(pol
e-noo
-kle-o-tı¯d)
Compound formed by the union of
many nucleotides; a nucleic acid.
p. 68
polypeptide
(pol
e-pep
tı¯d)
Compound
formed by the union of many amino
acid molecules. p. 116
polyploidy
(pol
e-ploi
de)
A cell
with one or more extra sets of
chromosomes. p. 929
polysaccharide
(pol
e-sak
ah-rı¯d)
Carbohydrate composed of many
joined monosaccharides. p. 62
pons
(ponz)
Part of the brainstem
above the medulla oblongata and
below the midbrain. p. 407
popliteal
(pop
lı˘-te
al)
Pertaining to the
region behind the knee. p. 24
positive chemotaxis
(poz
ı˘-tiv ke
mo-
tak
sis)
Movement of a cell toward
the greater concentration of a
substance. p. 533
positive Feedback
(poz
ı˘-tiv fe
¯d
bak)
Process by which changes cause
phospholipid
(fos
fo-lip
id)
Molecule
consisting of two fatty acids and a
phosphate group bound to a glycerol
molecule. p. 64
phosphorylation
(fos
for-ı˘-la
shun)
Metabolic process that adds a
phosphate to an organic molecule.
p. 119
photoreceptor
(fo
to-re-sep
tor)
Nerve
ending
sensitive to light energy.
p. 439
pH scale
(pH ska
¯l)
Shorthand notation
for the hydrogen ion concentration
used to indicate the acidic or
alkaline condition of a solution;
values range from 0 to 14. p. 59
physiology
(F z
e-ol
o-je)
The study of
body functions. p. 4
pia mater
(pi
ah ma
ter)
Inner layer of
meninges that encloses the brain
and spinal cord. p. 385
pineal gland
(pin
e-al gland)
Small
structure in the central part of the
brain that secretes the hormone
melatonin, which controls certain
biological rhythms. p. 407
pinocytosis
(pin
o-si-to
sis)
Process by
which a cell engulfs droplets of fl
uid
from its surroundings. p. 96
pituitary gland
(pı˘-tu
ı˘-ta
¯r
e gland)
Endocrine gland attached to the base
of the brain that consists of anterior
and posterior lobes; the hypophysis.
p. 492
pivot joint
(piv
ut joint)
End of a bone
moving within a ring formed by
another bone and connective tissue.
p. 266
placenta
(plah-sen
tah)
Structure that
attaches the fetus to the uterine wall,
delivering nutrients to and removing
wastes from the fetus. p. 512
placental lactogen
(plah-sen
tahl lak
to-
jen)
Hormone secreted by the
placenta that inhibits maternal
insulin activity during pregnancy.
p. 884
plantar
(plan
tar)
Pertaining to the sole
of the foot. p. 24
plantar fl
exion
(plan
tar fl
ek
shun)
Ankle movement that brings the foot
farther from the shin. p. 269
plasma
(plaz
mah)
±luid portion of
circulating blood. p. 523
plasma cell
(plaz
mah sel)
Type of
antibody-producing cell that forms
when activated B cells proliferate.
p. 633
plasma protein
(plaz
mah pro
te
¯n)
Protein dissolved in blood plasma.
p. 535
plasmin
(plaz
min)
Protein-splitting
enzyme that can digest F
brin in a
blood clot. p. 541
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