Across
- 4. Collagen fibers that link the skeletal muscle to bone.
- 5. end plate Ending of a motor nerve at a muscle fiber that delivers neural impulses and in turn activates the fiber.
- 6. Individual threadlike fibers that run lengthwise and parallel to one another within a muscle fiber and contain contractile units, or sarcomeres.
- 10. twitch fiber Type of muscle fiber that is red in appearance, aerobic, small, fatigue resistant, and has a slow speed of contraction.
- 11. nervous system The brain and spinal cord; regarded as the body’s control center.
- 12. Proteins that make up the sarcomere (i.e., actin and myosin).
- 14. A muscle or group of muscles opposing the action.
- 16. muscle The muscle of the heart that has characteristics of both smooth and skeletal muscle and is under involuntary control.
- 20. principle An impulse of a certain magnitude is required to cause the innervated fiber to contract.
- 22. fiber A cylinder-shaped cell that makes up skeletal muscle.
- 23. nervous system Nerve cells and fibers that lie outside the central nervous system; connects the central nervous system to the rest of the body.
Down
- 1. twitch fiber Type of muscle fiber that is white in appearance, anaerobic, large, fatigable, and has high contraction speed.
- 2. The thick myofilament that makes up the sarcomere.
- 3. adaptation During strength training, it is the body’s adaptation that leads to muscular performance improvements as reflected by the body’s increased strength.
- 7. coordination The capacity to activate motor units simultaneously.
- 8. muscle Forms the walls of blood vessels and body organs; under the control of the autonomic nervous system.
- 9. Contractile unit of a skeletal muscle that is organized within a myofibril in series (i.e., attached with other sarcomeres end to end).
- 10. muscle Muscle that is attached to bone; its contraction is responsible for supporting and moving the skeleton, and it is under voluntary control.
- 13. coordination The capacity to activate various muscles or muscle groups simultaneously to produce action.
- 14. The thin myofilament that makes up the sarcomere.
- 15. A muscle’s attachment that is closer to the center of the body; also known as its proximal attachment.
- 17. A connective tissue sheath that surrounds each muscle fiber or cell.
- 18. The muscle that supports or complements the action of a prime mover.
- 19. filament theory The phenomenon of muscle contraction, during which the sliding of the actin filaments over the myosin filaments causes shortening of the muscle to create movement.
- 21. Steadies the joint closer to the body axis so that the desired action can occur.