NSCI/280 Version 5 / 3
University of Phoenix Material
Animations: The Muscular System
Skeletal Muscle
After viewing the animation, answer these questions:
1. is responsible for voluntary movement of the human body.
2. What is the structure of these muscles?
3. What is the epimysium?
4. At the ends of the muscle, the epimysium is continuous with .
5. What is the perimysium?
6. What is a fascicle?
7. What is the endomysium?
8. A muscle fiber consists of .
9. What is unique about the nuclei of a muscle fiber? Where are they located?
10. What structures dominate the interior of the muscle fiber?
11. What are the two types of protein filaments that compose the myofibril?
12. Name the orderly contractile unit of the muscle fiber.
13. The shortened sarcomeres result in , and ultimately .
Neuromuscular Junction
After viewing the animation, answer these questions:
1. What sequence of events occurs when an action potential arrives at the presynaptic terminal?
2. What sequence of events occurs when the calcium ions enter the presynaptic terminal?
3. What is the function of acetylcholine?
4. The movement of ions into the muscle cell results in .
5. Once threshold has been reached .
6. What happens to the acetylcholine after the generation of an action potential on the muscle cell membrane?
Sliding Filament
After viewing the animation, answer these questions:
1. Describe the muscle myofilaments in a relaxed muscle.
2. What interaction do these myofilaments have during contraction?
3. What is the result?
4. Describe the muscle myofilaments in a fully contracted muscle.
Excitation-Contraction Coupling
After viewing the animation, answer these questions:
1. Action potentials are propagated over which structure of the skeletal muscle fiber?
2. How does the action potential arrive into the interior of the muscle fiber?
3. What does the entry of the action potential cause to occur inside the muscle fiber?
4. This causes ions to diffuse from the into the .
5. Where is the tropomyosin located? What is it covering?
6. Describe the molecules attached to the tropomyosin.
7. What events occur when the calcium ions bind to the troponin molecule?
8. How are cross-bridges formed?
Cross Bridge Cycle
After viewing the animation, answer these questions:
1. During contraction of a muscle, bind to . This moves out of the way and uncovers for on the .
2. What molecules are attached to the myosin head from the previous cycle of movement?
3. How are cross-bridges formed? What is released in the process?
4. How is the myosin head moved? What does this cause? What is released from the myosin head when this occurs?
5. How is the bond between the actin and myosin filaments broken? How is energy released? What happens to this energy?
6. After the myosin head returns to its upright position, what occurs if calcium ions are still present?
Reference
Broyles, R. B. (2012). Workbook to accompany anatomy & physiology revealed version 3.0. New York, NY: McGraw-Hill.