What molecular event terminates muscle contraction in skeletal muscle?

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Question: What molecular event terminates muscle contraction in skeletal muscle?

Option 1: ATP hydrolysis by myosin. This step powers the cross-bridge cycle and is essential for contraction to proceed, not for its termination. Once ATP binds and myosin detaches from actin, another cycle could begin if calcium remains high, so this is not the terminating event.

Option 2: Decrease in cytosolic calcium due to active uptake into the sarcoplasmic reticulum. This is the key terminating event. As calcium is pumped back into the sarcoplasmic reticulum by SERCA pumps, calcium levels fall, troponin returns to its inhibitory state on actin, and the actin-myosin interaction is halted, leading to relaxation and cessation of contraction.

Option 3: Detachment of acetylcholine from its receptor. This occurs at the neuromuscular junction and stops the neural signal that would otherwise trigger muscle contraction, but it does not directly terminate contraction once calcium is already elevated inside the muscle fiber. It prevents initiation of new contractions rather than terminating a current one.

Option 4: Breakdown of troponin by proteases. While troponin is involved in regulating contraction, its proteolytic breakdown is not the normal mechanism by which contraction ends. Troponin must remain functional to regulate calcium sensitivity; proteolysis is not the standard termination pathway for contraction.

In summary, the primary molecular mechanism terminating skeletal muscle contraction is the reduction of cytosolic calcium via active reuptake into the sarcoplasmic reticulum, which reverses the calcium-activated state that allows cross-bridge cycling.

PHYSIO 3200 AU2025 (33564) Quiz # 5 Dr. Heissler's content

What molecular event terminates muscle contraction in skeletal muscle?

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PHYSIO 3200 AU2025 (33564) Quiz # 5 Dr. Heissler's content

What molecular event terminates muscle contraction in skeletal muscle?

查看解析

登录即可查看完整答案

类似问题

Antagonists muscle group: A to B: EJ __extenders __ B to A: EJ __ extenders __ Antagonists are passively __ lengthening __ from A to B and passively __shortening __ from B to A.

Question1.20 Which of the following does NOT directly impact force production potential of a muscle? Muscle volume Muscle fibre type Neural recruitment frequency Muscle fibre Pinnation Muscle length ResetMaximum marks: 1 Flag question undefined

Stretching exercises are designed to lengthen the muscle tissue and help it relax to its normal resting state.

Which of the following best describes the function of the sarcoplasmic reticulum in skeletal muscle fibers?

Question at position 38 Why is the regulation of calcium in the sarcoplasm important for muscle function?To enhance the muscle's ability to relaxTo increase the availability of oxygen to the muscle fibersTo prevent muscle contraction from becoming too slowTo avoid abnormal muscle contraction

Muscle tissue has all of the following properties except ________.

Question at position 65 Skeletal muscle is considered voluntary because it cannot perform actions subconsciously.TrueFalse

Question at position 55 Which property of muscle tissue enables it to respond to a stimulus, such as a hormone or motor neuron signal?ContractilityElasticityExcitabilityExtensibility

更多留学生实用工具

希望你的学习变得更简单

Antagonists muscle group: A to B: EJ extenders B to A: EJ extenders Antagonists are passively lengthening from A to B and passively shortening from B to A.