Normally the acetylcholine receptor‒mediated channels in the motor end plate at a neuromuscular junction are closed.Which statement about this channel is true? A) The channel opens when acetylcholine passes through it. B) The binding of acetylcholinesterase opens the channel. C) Activation of the channel by the binding of acetylcholine causes Na⁺ ions to enter the presynaptic cell. D) When the channel opens, Na⁺ ions enter the muscle cell. E) When the channel opens, the cell becomes hyperpolarized.

Question

Quizplus · Accepted Answer

The channel opens when acetylcholine binds to it, which allows for the influx of Na+ and the depolarization of the muscle cell. Acetylcholinesterase breaks down acetylcholine in the synaptic cleft, but it does not directly affect the opening or closing of the receptor channel. The movement of ions into or out of the presynaptic cell is not related to the activation of the receptor channel. Hyperpolarization occurs when there is an increase in the membrane potential, which is not the case when the acetylcholine receptor channel opens.

Normally the Acetylcholine Receptor‒mediated Channels in the Motor End Plate