Nerves and Muscles

1. something from the environment that triggers a behavior or causes a reaction in an organism.
3. long, tube-shaped bundle of neurons that runs from the brainstem to the lower back and has the main function of carrying nerve impulses back and forth between the body and brain.
5. cell that transmits electrical impulses in the nervous system; commonly called a nerve cell.
7. reaction to a stimulus by a living organism.
8. specialized cells that convert external stimuli into neural impulses.
11. muscle Voluntary muscles attached to bone.

2. human body system that includes all the muscles of the body, coordinates movement, and produces heat; muscles and tendons are its main organs.
3. muscle Involuntary muscles located in the hollow internal organs.
4. muscle Involuntary muscles located in the heart.
5. one of many cable-like bundles of axons that make up the peripheral nervous system.
6. human body system that collects, transfers, and processes information; the brain, spinal cord, and nerves are its main organs.
9. main organ of the central nervous system that serves as the control center of the nervous system and of the body as a whole.
10. an automatic, involuntary response.