| A | B |
|---|
| acetylcholine | a neurotransmitter |
| actin | thin protein filament found in a muscle |
| action potential | electral change occurring across the membrane during the transmission of a nerve impulse |
| agonist | the muscle that causes a movement |
| antagonist | a muscle whose action opposes the action of another muscle |
| ataxia | lack of muscle coordination |
| cardiac muscle | heart muscle |
| extensor muscle | muscles that produce extension when it contracts |
| flaccid | lacking muscle tone |
| flexor muscle | muscles that produce flexion |
| hypertrophy | an increase in size of the muscle cell |
| myofibril | cylinder containing the thin and thick filament within the muscle fiber which give it its striated appearance |
| myopathy | muscle disease |
| myosin | thick protein filament found in muscle fibers |
| neuromuscular junction | point between the motor nerve axon and the muscle cell membrane |
| point of insertion | end of the muscle that is attached to the moving bone |
| point of origin | end of the skeletal muscle that is attached to the stationary part of the bone |
| prime mover | muscle that provides movement in a single direction (agonist) |
| sarcolemma | muscle cell membrane |
| sarcomere | portion of striated muscle fibril that lies between the two adjacent dark lines |
| sarcoplasmic reticulum | storage site for calcium within a muscle |
| skeletal muscles | voluntary muscles that attach to skeletal bones |
| smooth muscles | involuntary muscles found in lining of airways, blood vessels, and uterus |
| sphincter | muscular ring around a tube; a valve |
| tonus | a partial, steady contraction of a muscle |
| Z lines | lines visible on the surface of skeletal muscle that mark the ends of each sarcomere |
| atrophy | wasting away of a muscle |
