| A | B |
|---|
| acetylcholine | neurotransmitter; released at synapses within the nervous system and at the neuromuscular junction |
| actin | one of the two contractile proteins in muscle cells that are thin and light |
| agonist | muscle that contracts to perform a given movement |
| antagonist | muscle that has an action opposite that of a given movement or muscle |
| aponeurosis | broad sheet of fibrous connective tissue taht attaches muscle to bone or to other muscle |
| contractility | a muscle fiber's capacity to undergo shortening, becoming thicker |
| endomysium | the deepest layer of connective tissue that surrounds the individual fibers in the fascicles |
| epimysium | connective tissue sheath that encases the entire muscle |
| excitability | in cells, the ability to transmit an electric current along the plasma membrane |
| fascicle | small bundle, as of muscle cells or nerve cell fibers |
| glycogen | compound built from glucose molecules that is stored for energy in the liver and muscles |
| insertion | muscle attachment connected to a movable part |
| isometric | muscle contraction in which there is no change in muscle length but an increase in muscle tension, as in pushing against an immovable force |
| isotonic | describing a solution that has the same concentration as the fluid within a cell |
| motor unit | group consisting of a single neuron and all the muscle fibers it stimulates |
| myoglobin | compound that stores oxygen in muscle cells |
| myosin | one of the two contractile proteins in muscle cells; thick and dark |
| neuromuscular | pertaining to the point at which a neuron's axon contacts a muscle cell |
| neurotransmitter | chemical released from the ending of an axon that enables a nerve impulse to cross a synapse |
| origin | source; beginning; muscle attachment connected to a nonmoving part |
| perimysium | connective tissue layer around each fascicle |
| sarcomere | a contracting subunit of skeletal muscle |
| sarcoplasmic reticulum | intracellular membrane in muscle cells that is equivalent to the endoplasmic reticulum (ER) in other cells; stores calcium needed for muscle contraction |
| synapse | junction between two neurons or between a neuron and an effector |
| synergist | substance or structure that enhances the work of another. A muscle that works with a prime mover to produce a given movement |
| tendon | cord of fibrous connective tissue that attaches a muscle to a bone |
| tonus | partially contracted state of muscle; also, tone |
| tropomyosin | protein that works with troponin to regulate contraction in skeletal muscle |
| troponin | protein that works with tropomyosin to regulate contraction in skeletal muscle |
