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40 Cards in this Set
- Front
- Back
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Myosin
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A motor protein that constitutes the thick myofilaments of muscle and has globular, mobile heads of ATPase that bind to actin molecules.
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Excitability
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The ability of a cell to respond to a stimulus, especially the ability of nerve and muscle cells to produce membrane voltage changes in response to stimuli; irritability
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Synaptic Cleft
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A narrow space between the synaptic knob of an axon and the adjacent cell, across which a neurotransmitter diffuses.
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Synaptic Knobs
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The swollen tips of the distal branches of an axon; the site of synaptic vesicles and neurotransmitter release.
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Synaptic Vesicle
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A spheroid organelle in a synaptic knob containing neurotransmitter.
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Action Potential
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A rapid voltage change in which a plasma membrane briefly reverses electrical polarity; has self-propagating effect that produces a traveling wave of excitation in nerve and muscle cells.
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Threshold
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The minimum voltage to which the plasma membrane of a nerve or muscle cell must be depolarized before it produces an action potential.
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T Tubule
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A tubular extension of the plasma membrane of a muscle cell that conducts action potentials into the sarcoplasm and excites the sarcoplasmic reticulum.
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Electrochemical Gradient
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A difference in ion concentration from one point to another, resulting in a gradient of both chemical concentration and electrical charge.
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Excitation-Contraction Coupling
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Events that link the synaptic stimulation of a muscle cell to the onset of contraction.
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Calmodulin
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An intracellular protein that binds calcium ions and mediates many of the second messenger effects of calcium.
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Muscular Tissue
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A tissue composed of elongated, electrically excitable cells specialized for contraction; the three types are skeletal, cardiac, and smooth muscle.
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Myoglobin
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A red oxygen-storage pigment of muscle; supplements hemoglobin in providing oxygen for aerobic muscle metabolism.
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Length-Tension Relationship
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A law that relates the tension generated by muscle contraction to the length of the muscle fiber prior to stimulation; it shows that the greatest tension is generated when the fiber exhibits an intermediate degree of stretch before stimulation.
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Refractory period
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A period of time after a nerve or muscle cell has responded to a stimulus in which it cannot be reexcited by a threshold stimulus.
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Myofibril
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A bundle of myofilaments forming an internal subdivision of a cardiac or skeletal muscle cell.
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Acetylcholine
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A neurotransmitter released by somatic motor fibers, parasympathetic fibers, and some other neurons, composed of choline and an acetyl group.
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Creatine Phosphate
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An energy storage molecule in muscle that donates a phosphate group to ADP and thus regenerates ATP in periods of hypoxia.
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Endurance Exercise
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A form of physical exercise, such as running or swimming, that promotes cardiopulmonary efficiency and fatigue resistance more than muscular strength. Compare resistance exercise.
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Isotonic Contraction
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A muscle contraction in which the muscle shortens and moves a load while its internal tension remains constant.
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Elasticity
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The tendency of a stretched structure to return to its original dimensions when tension is released.
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Neuromuscular Junction
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A synapse between a nerve fiber and a muscle fiber.
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Sarcoplasmic Reticulum
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The smooth endoplasmic reticulum of a muscle cell, serving as a calcium reservoir.
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Scanning Electron Microscope
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A microscope that uses an electron beam in place of light to form high-resolution, three-dimensional images of the surfaces of objects; capable of much higher magnifications than a light microscope.
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Synapse
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A junction at the end of an axon where it stimulates another cell.
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Isometric Contraction
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A muscle contraction in which internal tension rises but the muscle doesn't shorten.
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Latent Period
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The interval between a stimulus and response, especially in the action of nerve and muscle cells.
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Myofilament
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A protein microfilament responsible for the contraction of a muscle cell, composed mainly of myosin or actin.
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Calsequestrin
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A protein found in smooth endoplasmic reticulum that reversibly binds and stores calcium ions, rendering calcium chemically unreactive until needed for such processes as muscle contraction.
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Isotonic
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Having the same osmotic pressure as human cells or some other reference solution.
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Motor End Plate
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A depression in a muscle fiber where it has symaptic contact with a nerve fiber and has a high density of neutotransmitter receptors.
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Motor Unit
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One motor neuron and all the skeletal muscle fibers innervated by it.
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Muscle Tone
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A state of continual, partial contraction of resting skeletal or smooth muscle.
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Norepinephrine
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A catecholamine that functions as a neurotransmitter and adrenal hormone, especially in the sympathetic nervous system.
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Peristalsis
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A wave of constriction traveling along a tubular organ such as the esophagus or ureter, serving to propel its contents.
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Acetylcholinesterase
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An enzyme that hydrolyzes acetylcholine, thus halting signal transmission at a cholinergic synapse.
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All-Or-None Law
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A statement pertaining to action potentials and the contraction of muscle fibers that a cell either produces its maxiumum response or no response at all, depending on whether the stimulus is above or below threshhold.
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Resting Membrane Potential
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A stable voltage across the plasma membrane of an unstimulated cell.
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Sarcomere
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In skeletal and cardiac muscle, the portion of a myofibril from one Z disc to the next, constituting one contractile unit.
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Smooth Muscle
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Nonstriated involuntary muscle found in the walls of the blood vessels, many of the viscera, and other places
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