Reference no: EM133477033
Assignment: Physiological Reasoning Activity: Muscles
Neural activation of skeletal muscle involves a sequence of steps. Understanding the steps in this sequence helps you to determine the locus of disturbances that affect muscle contraction.
You are given an isolated muscle with its motor nerve intact. This preparation is arranged so that you can make electrophysiological measurements from the nerve and muscle as well as mechanical measurements of muscle contraction. You observe that if caffeine is added to the fluid bathing the muscle preparation, the peak tension developed in the muscle twitch produced by stimulating the motor nerve is increased.
Question A. Describe the possible locations at the neuromuscular junction (the nerve ending and muscle) at which caffeine may exert its effect. (Hint: Be sure to think of all the steps involved in generating a muscle contraction starting from the nerve - see mini-lecture on skeletal muscle for review)
Question B. Caffeine is known to alter transmembrane movement of calcium. What are two possible sites/proteins in the nerve and/or muscle that caffeine can act upon?
Question C. What might happen to muscle contraction if acetylcholinesterase were added to the preparation?
Question D. If you were to induce muscle contractions at a level that mimics high-intensity exercise (90% maximum), what fuel(s) would you need to provide the muscle? How might that change if you were to mimic 20% exercise intensity?
Question E. If you accidentally add too much caffeine to the preparation, the muscle stays contracted. Explain what is happening and what you might expect to see after some time.
Question F. A motor unit includes a neuron and all of the muscle fibers it innervates. Explain how the innervations and measurements of muscle tension might differ if the preparation was an eye muscle as compared to the quadriceps.