The release of neurotransmitter molecules from buttons is often triggered by
A) an efflux of sodium ions.
B) an influx of calcium ions.
C) the sodium-potassium pump.
D) the arrival of an AP at the axon hillock.
E) the release of calcium ions from the buttons.

Question

Quizplus · Accepted Answer

When an action potential arrives at the axon terminal, it triggers the opening of voltage-gated calcium channels. Calcium ions then rush into the axon terminal, which triggers the release of neurotransmitter molecules from vesicles within the terminal into the synaptic cleft. Therefore, the influx of calcium ions (choice B) is responsible for triggering the release of neurotransmitter molecules from the buttons. The other options listed (efflux of sodium ions, sodium-potassium pump, arrival of an action potential at the axon hillock, and release of calcium ions from the buttons) are not directly involved in triggering the release of neurotransmitter molecules from axon terminals.

The Release of Neurotransmitter Molecules from Buttons Is Often Triggered