Neurotransmitters being released by a presynaptic neuron into the synapse are due to,____.
A) the neuron being in a refractory period
B) a large concentration of Na+ ions outside of the presynaptic axon
C) a high concentration of negative ions inside the neuron
D) action potentials that have occurred in the presynaptic neuron

Question

Quizplus · Accepted Answer

Neurotransmitters are released by presynaptic neurons in response to action potentials that have occurred in that neuron. When an action potential reaches the end of a presynaptic axon, it causes voltage-gated calcium channels to open. The influx of calcium ions triggers the release of neurotransmitters into the synapse. Therefore, option D is the best choice because it correctly explains how neurotransmitter release occurs.

Neurotransmitters Being Released by a Presynaptic Neuron into the Synapse