PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Lack of calcium ions attach to tropomyosin
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Lack of ATP attach to the myosin head
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Muscle stiff due to lack of heat
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Lactic acid accumulates in muscle
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Detailed explanation-1: -The main cause of rigor mortis is depletion of the cell’s energy molecule, ATP. ATP separates actin-myosin bridges during muscle relaxation. Without ATP, cross-bridging locks muscles in place. Eventually, decomposition breaks the bridges and muscles relax.
Detailed explanation-2: -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-3: -When oxygen is no longer present, the body may continue to produce ATP via anaerobic glycolysis. When the body’s glycogen is depleted, the ATP concentration diminishes, and the body enters rigor mortis because it is unable to break those bridges. Calcium enters the cytosol after death.
Detailed explanation-4: -Rigor mortis occurs because muscle cells are no longer supplied with ATP (when breathing stops, ATP synthesis ceases). Calcium also flows freely into dying cells. The rigor eventually disappears because the biological molecules break down.