Question

Which one of the following ions uses the second ion channel to open during an action potential, acts as a second messenger once in the neuron, activates the release of neurotransmitter, and activates ion channels that allow for influx of other ions that halt the action potential?

A. Na+
B. K+
C. Cl−
D. Ca2+
E. IP3

Answer 1

Ca2+ ions play a critical role in neuron signaling by opening the second ion channel during an action potential, serving as a second messenger, and initiating neurotransmitter release and the influx of other ions that help terminate the potential.

Step-by-step explanation:

The ion that uses the second ion channel to open during an action potential, acts as a second messenger once in the neuron, activates the release of neurotransmitter, and activates ion channels allowing for the influx of other ions that halt the action potential, is Ca2+. Calcium ions (Ca2+) entering the neuron trigger a cascade of events leading to neurotransmitter release, which can then bind to receptors on another cell to propagate the signal.

Additionally, the release of calcium from internal stores like the smooth endoplasmic reticulum during an action potential contributes to processes such as calcium-induced calcium release (CICR) in muscle cells.