PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Rigor mortis occurs when
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the lack of calcium causes ATP to bind to troponin blocking the actin binding site and prevents muscles from relaxing
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there is no more ATP to allow for the myosin heads to detach from the binding sites on the actin.
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acetylcholine is degraded by acetylcholinesterase and results in increase production of calcium resulting in excess contractions of the muscle.
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there is no more oxygen present. This reduces the amount of FADH2 in the electron transport chain of the sarcolemma resulting in muscles that cannot relax.
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Explanation:
Detailed explanation-1: -When ATP binds to troponin, it prevents cross-bridges from forming between actin and myosin filaments, resulting in irreversible muscle rigidity. ATP provides the energy for the actin-myosin cross-bridge to detach, which prevents the muscle from relaxing, resulting in rigor mortis.
Detailed explanation-2: -One part of the myosin head attaches to the binding site on the actin, but the head has another binding site for ATP. ATP binding causes the myosin head to detach from the actin (Figure 4d).
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