ch 4

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