Muscles

2. Sheath that surrounds muscle fascicles
5. A bundle of structures such as muscle fibers
7. a rod shaped organelle in muscle cells that is responsible for muscle contraction
11. A flexible but inelastic cord of strong fibrous collagen tissue attaching to a muscle or bone
12. Neurotransmitter that carries chemical messages and stimulates muscle contraction
13. A dark band in the sarcomere, the primary unit of muscle structure
15. The ability of muscles to return to their original length after being shortened or stretched
16. A lighter band of skeletal muscle that contains micofilaments of actin
17. Thin layer of connective tissue surrounding muscle fiber
18. A motor neuron and the muscle fibers it controls
20. A cellular structure in stightened muscles that marks the sarcomere

1. The connection between a motor nerv and a muscle fiber
3. A protein that converts chemical energy into
4. The cells's ability to respond to stimuli by changing its membrane potential
6. Dense connective tissue that surrounds the entire muscle
8. The ability of a muscle to be stretched or extended without tearing
9. The ability of the body to become shorter or smaller
10. A protein that helps cells move, contract, and maintain their structure
14. The basic unit of muscle that contracts to generate force and support load
19. A region in skeletal muscle fibers that appears lighter than surrounding A Band