Question

When an action potential reaches the end of the axon, what happens?
The potassium ions travel back toward the cell body.
The neuron takes up chemical messengers (neurotransmitters).
The sodium ions travel back toward the dendrites.
The neuron releases chemical messengers (neurotransmitters).

Answer 1

The neuron releases chemical messengers (neurotransmitters).

The end of an axon tends to be a synapse, this is a very small gap between neurones, when an action potential reaches a synapse, the depolarisation of the membrane causing an influx of ions, usually calcium ions which trigger the translocation of vesicles containing neurotransmitters to the cell membrane, where the synapse is, the vesicles fuse with the membrane and release the neurotransmitters, which bind to receptors of the other axon membrane, causing depolarisation and continuation of the action potential.
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