When an action potential arrives at an axon terminal, the fusion of neurotransmitter vesicles with the cell membrane is triggered by A) an increase in the concentration of calcium ions within the cell. B) the removal of calcium ions from the cytoplasm of the cell. C) the opening of K⁺ leak channels, which causes an increase in potassium ions within the cell. D) the release of acetylcholine. E) a sudden increase in chloride ions within the cytoplasm of the cell.

Question

Quizplus · Accepted Answer

The fusion of neurotransmitter vesicles with the cell membrane is triggered by an increase in the concentration of calcium ions within the cell. This influx of calcium ions is caused by the opening of voltage-gated calcium channels in response to the action potential. The calcium ions then bind to the synaptic vesicles, causing them to fuse with the cell membrane and release their contents (neurotransmitters) into the synaptic cleft.

When an Action Potential Arrives at an Axon Terminal, the Fusion