PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Calcium binds to actin
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The muscle contracts
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Calcium binds to troponin
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Calcium binds to myosin
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Detailed explanation-1: -Because terminal cisternae ensure rapid calcium delivery, they are well developed in muscles that contract quickly, such as fast twitch skeletal muscle. Terminal cisternae then go on to release calcium, which binds to troponin. This releases tropomyosin, exposing active sites of the thin filament, actin.
Detailed explanation-2: -On excitation, small amounts of Ca2+ enter from the transverse tubule and interact with a Ca2+ enter from the transverse tubule and interact with a Ca2+ receptor at the terminal cisternae and cause Ca2+ release (Ca2+-induced Ca2+ release).
Detailed explanation-3: -When calcium binds to troponin, the troponin changes shape, removing tropomyosin from the binding sites. The sarcoplasmic reticulum stores calcium ions, which it releases when a muscle cell is stimulated; the calcium ions then enable the cross-bridge muscle contraction cycle.