er-us) Highly convoluted tubes within
the testes; form sperm.
Localized collections of many types of cells working to-
gether to accomplish a speciﬁc receptive process.
Sensory (aﬀerent) nerves
Nerves that contain processes of sensory neu-
rons and carry impulses to the central nervous system.
Functional areas of the cerebral cortex that provide for
conscious awareness of sensation.
A cell or part of a cell (e.g., receptive endings of sen-
sory neurons) specialized to respond to a stimulus.
Serosa (serous membrane)
sah) Te moist membrane found in
closed ventral body cavities.
us) Clear, watery ﬂuid secreted by cells of a serous
um) Amber-colored ﬂuid that exudes from clotted blood as
the clot shrinks; plasma without clotting factors.
ah-moid) Short bones embedded in tendons, vari-
able in size and number, many of which inﬂuence the action of muscles;
largest is the patella (kneecap).
Severe combined immunodeﬁciency syndromes (SCIDs)
conditions resulting in little or no protection against disease-causing or-
ganisms of any type.
Te chromosomes, X and Y, that determine genetic
male); the 23rd pair of chromosomes.
Inherited traits determined by genes on the sex
chromosomes, e.g., X-linked genes are passed from mother to son, Y-
linked genes are passed from father to son.
Sexually transmitted infection (STI)
Any infectious disease spread
through sexual contact.
A short peptide segment present in a protein being syn-
thesized that causes the associated ribosome to attach to the membrane
of rough ER.
Te unassisted transport across a plasma membrane of
a lipid-soluble or very small particle.
Sinoatrial (SA) node
tre-al) Specialized myocardial cells in the
wall of the right atrium; pacemaker of the heart.
nus) (1) Mucous-membrane-lined, air-ﬁlled cavity in certain
cranial bones; (2) dilated channel for the passage of blood or lymph.
Muscle composed of cylindrical multinucleate cells with
obvious striations; the muscle(s) attached to the body’s skeleton; volun-
System of protection and support composed primarily
of bone and cartilage.
Bony protective encasement of the brain and the organs of hearing
and equilibrium; includes cranial and facial bones.
Convoluted tube extending from the pyloric sphincter to
the ileocecal valve where it joins the large intestine; the site where diges-
tion is completed and virtually all absorption occurs.
Spindle-shaped cells with one centrally located nucleus
and no externally visible striations (bands). Found mainly in the walls of
A primary active transport system
that simultaneously drives Na
out of the cell against a steep gradient
and pumps K
back in. Also called Na
Reversible change of a colloid from a ﬂuid (sol)
to a more solid (gel) state.
RNA (ribonucleic acid)
ik) Nucleic acid that contains
ribose and the bases A, G, C, and U. Carries out DNA’s instructions for
One of the two types of photosensitive cells in the retina.
Te turning of a bone around its own long axis.
ge) Elevations or ridges, as in stomach mucosa.
Rule of nines
Method of computing the extent of burns by dividing
the body into a number of areas, each accounting for 9% (or a multiple
thereof) of the total body area.
S (synthetic) phase
Te part of the interphase period of the cell cycle in
which DNA replicates itself, ensuring that the two future cells will receive
identical copies of genetic material.
ĭ-tal) A longitudinal (vertical) plane that divides the
body or any of its parts into right and le² portions.
Secretion of the salivary glands; cleanses and moistens the mouth
and begins chemical digestion of starchy foods.
±ransmission of an action potential along a my-
elinated ﬁber in which the nerve impulse appears to leap from gap to gap.
Te plasma membrane of a muscle ﬁber.
ko-mēr) Te smallest contractile unit of muscle; extends
from one Z disc to the next.
Te nonﬁbrillar cytoplasm of a muscle ﬁber.
Sarcoplasmic reticulum (SR)
ized endoplasmic reticulum of muscle cells.
A type of supporting cell in the PNS; forms myelin sheaths
and is vital to peripheral nerve ﬁber regeneration.
rah) White opaque portion of the ﬁbrous layer of the eyeball.
tum) External sac enclosing the testes.
Sebaceous glands (oil glands)
shus) Epidermal glands that pro-
duce an oily secretion called sebum.
bum) Oily secretion of sebaceous glands.
A burn in which the epidermis and the upper re-
gion of the dermis are damaged.
Intracellular molecule generated by the binding of a
chemical (hormone or neurotransmitter) to a receptor protein; mediates
intracellular responses to the chemical messenger.
Secondary sex characteristics
Anatomical features, not directly in-
volved in the reproductive process, that develop under the inﬂuence of
sex hormones, e.g., male or female pattern of muscle development, bone
growth, body hair distribution.
shun) (1) Te passage of material formed by a cell to
its exterior; (2) cell product that is transported to the exterior of a cell.
Secretory vesicles (granules)
Vesicles that migrate to the plasma mem-
brane of a cell and discharge their contents from the cell by exocytosis.
A cut through the body (or an organ) that is made along a par-
ticular plane; a thin slice of tissue prepared for microscopic study.
During meiosis, the distribution of the members of the al-
lele pair to diﬀerent gametes.
Selectively permeable membrane
A membrane that allows certain
substances to pass while restricting the movement of others; also called
diﬀerentially permeable membrane.
men) Fluid mixture containing sperm and secretions of the
male accessory reproductive glands.
ner) Valves that prevent blood return to
the ventricles a²er contraction; aortic and pulmonary valves.