The Release of Acetylcholine from the Terminal of a Motor

Question

The release of acetylcholine from the terminal of a motor neuron is most directly linked to
A) the entry of potassium into the axon terminal.
B) the exit of potassium from the axon terminal.
C) the entry of sodium into the axon terminal.
D) the exit of sodium from the axon terminal.
E) the entry of calcium into the axon terminal.

Accepted Answer

The release of acetylcholine from the terminal of a motor neuron is most directly linked to the entry of calcium into the axon terminal. This influx of calcium ions triggers the release of acetylcholine into the synaptic cleft, where it can then bind to receptors on the muscle fiber and initiate muscle contraction. Therefore, choice E is the correct answer.