Which of the following normally terminates muscle contraction?
A)Depletion of ACh in the neuromuscular junction
B)Binding of ACh to the NM receptors
C)Pumping of calcium back into the sarcoplasmic reticulum
D)Depletion of ATP within the sarcomere

Question

Quizplus · Accepted Answer

Muscle contraction is initiated by the release of calcium ions from the sarcoplasmic reticulum, which binds to the troponin-tropomyosin complex and allows for actin-myosin interaction. The termination of muscle contraction occurs when calcium ions are pumped back into the sarcoplasmic reticulum by the Ca2+-ATPase pump, which restores the low concentration of calcium ions in the cytosol and allows for the troponin-tropomyosin complex to return to its inhibitory state. Therefore, choice C, pumping of calcium back into the sarcoplasmic reticulum, is the best answer. Choices A and B describe the events that occur during the initiation of muscle contraction and choice D does not contribute to the termination of muscle contraction.

Which of the Following Normally Terminates Muscle Contraction