GENERAL ANATOMY
MUSCLE ANATOMY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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a lack of ATP to allow the return stroke of the myosin head
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a lack of Calcium to allow the return stroke of the myosin head
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a lack of ATP to cause the power stroke of the myosin head
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a lack of Calcium to cause the power stroke of the myosin head
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Detailed explanation-1: -Without ATP present, the myosin head remains bound and the contraction is sustained. The depletion of ATP is thus the cause of rigor mortis, causing stiffness due to myosin’s inability to detach from actin.
Detailed explanation-2: -Without ATP, myosin stays locked onto actin, even if the muscle is trying to relax. Thus, when living muscle finally runs out of ATP after slaughter, then rigor mortis develops.
Detailed explanation-3: -Rigor mortis is a postmortem change resulting in the stiffening of the body muscles due to chemical changes in their myofibrils. Rigor mortis helps in estimating the time since death as well to ascertain if the body had been moved after death.
Detailed explanation-4: -After death, the body does not produce ATP. Because ATP is needed to detach the filaments of actin and myosin from one another, in the absence of ATP, the filaments become permanently complex and rigor mortis develops.
Detailed explanation-5: -Step 2: ATP binding to the myosin head domain induces a small conformational shift in the actin-binding site that reduces its affinity for actin and causes the myosin head to release the actin filament.