PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Calcium Ion Binding to the channel protein.
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Acetylcholine binding to the channel protein.
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Electrical Signal opening the channel protein.
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Acetylcholinesterase binding to the channel protein.
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Detailed explanation-1: -The acetylcholine binds to the nicotinic receptors concentrated on the motor end plate, a specialized area of the muscle fibre’s post-synaptic membrane. This binding causes the nicotinic receptor channels to open and let sodium ions enter the muscle fibre.
Detailed explanation-2: -Ligand-gated Na+ channels are found in the postsynaptic membrane of the neuromuscular junction. After a neurotransmitter (acetylcholine) binds to its receptor the channel opens (undergoes a conformational change) allowing Na+ to enter the motor endplate and K+ to flow out. This causes the motor endplate to depolarise.
Detailed explanation-3: -When acetylcholine binds to the receptors on a skeletal muscle cell, ion channels in that cell open, and this launches a sequence of events that results in contraction of the cell.