1. Please explain the steps involved in muscle contraction starting from stimula
ID: 3517707 • Letter: 1
Question
1. Please explain the steps involved in muscle contraction starting from stimulation of sciatic nerve to the power stroke of the myosin head. 2. What is happening in a muscle that is exhibiting: treope, summation, incomplete tetanus, and complete tetanus. Include molecular events and major characteristics. 3. Why do we see a graded response in single muscle twitch when increasing stimulus that is applied to sciatic nerve? 4. Describe what is occurring in the graph below at the level of the sarcomere? (100 is optimal length of the sarcomere) 100 E 80 360 6 40 2 20 40 0 100 120 140 160 Decreased length ncreasod ength 5. Why is there a latency period in the muscle contraction in our lab experiment? Between the contraction and relaxation period seen in the single muscle twitch which period is expected to be longer in duration and why?Explanation / Answer
Answer 1. Steps of muscle contraction
Nerve stimulation- generation of action potential- release of calcium from sarcoplasmic reticulum- sliding of actin over myosin- formation of cross bridge between actin and myosin- muscle contraction
Answer 2. Treppe is gradually increasing force of contraction in muscle fibers. Summation means addition of small stimulus of the muscle fibers. Incomplete tetanus means incomplete contraction of muscle fibers. Complete tetanus means sudden contraction of muscle. It is due to decrease in calcium concentration in the blood plasma.
Answer 3. With increasing stimulus we see graded response in single muscle twitch because of graded recruitment of the motor unit in the muscle fibers. With increasing stimulus more of motor unit is recruited and thus increasing the force of muscle contraction.
Answer 4. Sarcomere is the structural and functional unit of muscle contraction. As in the graph, it is shown that with increasing tension the length of sarcomere is increased up to a level then it is decreasing. This is due to cross bridge formation between actin and myosin.
Answer 5. Latency period seen in muscle contraction due to refractory period in the action potential of the muscle. During this refractory period the muscle can not be stimulated again. Between contraction and relaxation in single muscle twitch the contraction in longer in duration due to the presence of refractory period .
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