MUSCLE PHYSIOLOGY

PHYSIOLOGY

MUSCLE CONTRACTION

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

Out of the steps listed, which occurs before the others in muscle contraction?

A	Calcium Ion Enters the Pre-synaptic Terminal
B	Acetylcholine Enters the Synaptic Cleft
C	Sodium Ion Enters the Sarcolemma
D	Calcium Ion Enters the Sarcoplasm (Cytoplasm).

Explanation:

Detailed explanation-1: -(1) Calcium binds to troponin C, causing the conformational shift in tropomyosin that reveals myosin-binding sites on actin. (2) ATP then binds to myosin. (3) ATP is then hydrolyzed. (4) A cross-bridge forms and myosin binds to a new position on actin.

Detailed explanation-2: -During muscle contraction, high concentrations of calcium are required to displace troponin and reveal the active site at which myosin binds to for the power stroke. Calcium is released from the sarcoplasmic reticulum through calcium ion channels when the membrane of the T-tubular system is excited.

There is 1 question to complete.