Te response of a muscle to a single brief threshold
A group of inherited muscle-destroying diseases.
Te organ system consisting of the skeletal muscles of
the body and their connective tissue attachments.
Myelencephalon (spinal brain)
A secondary brain vesicle; lower part of
the developing hindbrain, especially the medulla oblongata.
ĕ-lin) Fatty insulating sheath that surrounds all but
the smallest nerve ﬁbers.
Embryonic mesoderm cells from which all muscle ﬁbers
Myocardial infarction (MI)
characterized by dead tissue areas in the myocardium; caused by inter-
ruption of blood supply to the area. Commonly called heart attack.
de-um) Layer of the heart wall composed of
bril) Rodlike bundle of contractile ﬁlaments (myoﬁla-
ments) found in muscle ﬁbers (cells).
ah-ment) Filament that constitutes myoﬁbrils. Of
two types: actin and myosin.
bin) Oxygen-binding pigment in muscle.
A graphic recording of mechanical contractile activity pro-
duced by an apparatus that measures muscle contraction.
tre-um) Tick uterine musculature.
pe-ah) A condition in which visual images are focused in
front of rather than on the retina; nearsightedness.
o-sin) One of the principal contractile proteins found in
mah) Condition resulting from underactive thy-
Natural killer (NK) cell
Defensive cell (a type of lymphocyte) that can
kill cancer cells and virus-infected body cells before the adaptive immune
system is activated.
sis) Death or disintegration of a cell or tissues caused
by disease or injury.
Negative feedback mechanisms
Te most common homeostatic con-
trol mechanism. Te net eﬀect is that the output of the system shuts oﬀ
the original stimulus or reduces its intensity.
Te four-week period immediately a±er birth.
o-plazm) An abnormal mass of proliferating cells. Benign
neoplasms remain localized; malignant neoplasms are cancers, which can
spread to other organs.
ron) Structural and functional unit of the kidney; consists
of the renal corpuscle and renal tubule.
A bundle of axons in the peripheral nervous system.
Axon of a neuron.
Nerve growth factor (NGF)
Protein that promotes survival and develop-
ment of neurons; secreted by their target cells and many other cell types.
A self-propagating wave of depolarization; also called an
Interlacing nerve networks that occur in the cervical,
brachial, lumbar, and sacral regions and primarily serve the limbs.
Fast-acting control system that triggers muscle contrac-
tion or gland secretion.
Inorganic chemical compounds found in nature; salts.
dre-ah) Cytoplasmic organelles responsible
for A²P generation for cellular activities.
Process during which the chromosomes are redistributed to two
daughter nuclei; nuclear division. Consists of prophase, metaphase, ana-
phase, and telophase.
Mitotic (M) phase
One of two major periods in the cell life cycle; in-
volves the division of the nucleus (mitosis) and the division of the cyto-
Mitral (bicuspid) valve
tral) Te le± atrioventricular valve.
Nerves containing the processes of motor and sensory
neurons; their impulses travel to and from the central nervous system.
lar) (1) A solution concentration determined by mass of
solute—1 liter of solution contains an amount of solute equal to its
molecular weight in grams. (2) Broad back teeth that grind and crush.
ĭ-te) A way to express the concentration of a solution;
moles per liter of solution.
(mōl) A mole of any element or compound is equal to its atomic
weight or its molecular weight (sum of atomic weights) measured in grams.
Particle consisting of two or more atoms joined together by
nal) Pure preparations of identical
antibodies that exhibit speciﬁcity for a single antigen.
o-sīt) Large single-nucleus white blood cell; agranular
ah-rīd) Literally, one sugar; building block
of carbohydrates; e.g., glucose.
u-lah) Te mulberry-like solid mass of blastomeres result-
ing from cleavage in the early conceptus.
Functional areas in the cerebral cortex that control volun-
tary motor functions.
Motor (eﬀerent) nerves
Nerves that carry impulses leaving the brain
and spinal cord, and destined for eﬀectors.
A motor neuron and all the muscle cells it stimulates.
Mucous membranes (mucosae)
Membranes that form the linings of
body cavities open to the exterior (digestive, respiratory, urinary, and
kus) A sticky, thick ﬂuid secreted by mucous glands and
mucous membranes; keeps the free surface of membranes moist.
kle-āt) Cell with more than one nucleus,
e.g., skeletal muscle cells, osteoclasts.
Multiple sclerosis (MS)
Demyelinating disorder of the CNS; causes
hardened patches (sclerosis) in the brain and spinal cord.
Neurons with three or more processes; most com-
mon neuron type in the CNS.
ik) Acetylcholine-binding receptors
of the autonomic nervous system’s target organs; named for activation by
the mushroom poison muscarine.
A muscle cell.
Encapsulated receptor found in skeletal muscle that is
sensitive to stretch.
Te force exerted by a contracting muscle on some
Low levels of contractile activity in relaxed muscle; keeps
the muscle healthy and ready to act.