Question | Answer |
fascia | layers of fibrous connective tissue that separate an individual skeletal muscle from adjacent muscles and hold it in position |
aponeuroses | a sheet of connective tissue by which certain muscles are attached to adjacent muscles |
myofibrils | contractile fibers within muscle cells |
myosin | a protein that, with actin, contracts and relaxes muscle fibers |
actin | a protein that, with myosin, contracts muscle fibers |
sarcomere | the segment of a myofibril from one Z line to the next Z line |
sarcoplasmic reticulum | membranous network of channels and tubules within a muscle fiber corresponding to the endoplasmic reticulum of other cells |
transverse tubules | membranous channel that extends inward from a muscle fiber membrane and passes through the fiber |
motor neuron | a neuron that transmits impulses from the central nervous system to an effector |
motor unit | a motor neuron and its associated muscle fibers |
motor end plate | specialized portion of muscle fiber membrane at a neuromuscular junction |
neuromuscular junction | point of contact between a nerve cell and muscle cell |
neurotransmitter | chemical that an axon end secretes to stimulate a muscle fiber to contract or a neuron to fire an impulse |
troponin and tropomyosin | proteins that are part of the actin filament |
ATPase | enzyme that causes ATP molecules to release the energy stored in their terminal phosphate bonds |
acetylcholine | a type of neurotransmitter, which is a biochemical secreted at axon ends of many neurons, transmits nerve messages across synapsis |
acetylcholinesterase | an enzyme that catalyzes breakdown of acetylcholine |
creatine phosphate | a muscle biochemical that stores energy |
myoglobin | temporarily stores oxygen and reduces a muscle's requirement for a continuous blood supply during muscular contraction |
oxygen debt | the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose |
all-or-none response | phenomenon in which a muscle fiber completely contracts when it is exposed to a stimulus of threshold strength |
summation | increased force of contraction by a skeletal muscle fiber when twitches occur so rapidly that the next twtich occurs before the previous twitch relaxes |
recruitment | an increase in the number of motor units being activated |
muscle tone | even when a muscle appears to be at rest, a certain amount of sustained contraction is occurring in its fibers |
multiunit smooth muscle | the muscle fibers are separate rather than organized into sheets |
visceral smooth muscle | composed of sheets of spindle-shaped cells in close contact with one another |
peristalsis | rhythmic waves of muscular contraction in the walls of certain tubular organs; due to transmission of impulses from cell to cell and rhythmicity |
origin | the immovable end of the muscle |
insertion | movable end of muscle |
prime mover (agonist) | muscle responsible for a particular body movement |
antagonist | resist a prime movers action and cause the movement in the opposite direction |
synergists | muscles that contract and assist the prime mover |