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Multiple Choice
What is the first event in muscle fiber contraction?
A
Binding of acetylcholine to receptors on the muscle fiber
B
Formation of cross-bridges between actin and myosin
C
Hydrolysis of ATP to ADP and inorganic phosphate
D
Release of calcium ions from the sarcoplasmic reticulum
Verified step by step guidance
1
Understand that muscle contraction is initiated by a signal from the nervous system, which involves the release of a neurotransmitter.
Identify the role of acetylcholine, a neurotransmitter, which is released at the neuromuscular junction and binds to receptors on the muscle fiber's membrane.
Recognize that the binding of acetylcholine to its receptors triggers an action potential in the muscle fiber, leading to a series of events that result in muscle contraction.
Acknowledge that the action potential causes the release of calcium ions from the sarcoplasmic reticulum into the cytosol of the muscle cell.
Note that the increase in calcium ion concentration allows for the formation of cross-bridges between actin and myosin, facilitated by the hydrolysis of ATP, which ultimately leads to muscle contraction.