| actin |
A contractile protein of muscle that makes up the thin filaments in the myofibrils of muscle fibers |
| capillaries |
The smallest blood vessels that carry blood; located between an arteriole and a venule |
| fascicle |
Bundles of skeletal muscle fibers |
| insertion |
End of muscle that moves during contraction; attached to a movable bone |
| motor unit |
Somatic motor neuron and all the muscle fibers that it stimulates |
| myofibril |
Basic unit of a muscle; contain actin and myosin filaments; has many sarcomeres |
| myosin |
A principal contractile proteins found in muscle; forms thick filaments in myofibrils of muscle fibers |
| neurotransmitter |
Chemical released by a neuron, stored at the ends of axons; stimulates neurons or effector cells; responsible for transmission of signals from one neuron to the next across a synapse |
| origin (of muscle) |
The end of muscle attached to the bone that remains stationary during muscular contraction |
| oxygen debt |
The amount of oxygen required to metabolize lactate after exercise |
| sarcomere |
Contractile unit of a myofiber; a bundled unit of thick and thin myofilaments whose contraction produces muscle contraction |
| sarcoplasmic reticulum |
Specialized smooth endoplasmic reticulum of skeletal muscle cells; surrounds the myofibrils and stores the calcium ions for muscle contraction |
| tendon |
A cordlike, strong band of tissue in the body that joins a muscle to a bone; made of collagen protein |
