MUSCLE NERVE CARTILAGE BONE
SKELETAL MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Which of these options best summarizes the THIRD and final phase of a muscle contraction?
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A stimulus from the neuron reaches the muscle fiber and stimulates an action potential in the muscle.
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The action potential travels along the sarcolemma and penetrates into the muscle fiber. Calcium is released by the SR and travels to the sarcomere.
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The cross bridge cycle occurs after calcium is released by the SR. During this cycle, the actin myofilaments are pulled towards the M line by the myosin myofilaments.
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None of the above
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Explanation:
Detailed explanation-1: -The following steps are involved in muscle contraction: (3) The axon branches to supply a number of muscle fibers called a motor unit, and the action potential is conveyed to a motor end plate on each muscle fiber.
Detailed explanation-2: -A single muscle twitch has a latent period, a contraction phase when tension increases, and a relaxation phase when tension decreases.
Detailed explanation-3: -This next phase is called the contraction phase. During the contraction phase the cross-bridges between actin and myosin form. Myosin moves actin, releases and reforms cross-bridges many times as the sarcomere shortens and the muscle contracts. ATP is used during this phase and energy is released as heat.
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