What action occurs at the synapse when a nerve impulse reaches the end of an axon?

When a nerve impulse reaches the end of an axon, the action that occurs is the release of neurotransmitters. This is a crucial event in communication between neurons. The arrival of the nerve impulse triggers a change in the electrical state of the presynaptic neuron, which leads to the opening of voltage-gated calcium channels. Calcium ions then flow into the neuron, facilitating the fusion of synaptic vesicles with the presynaptic membrane, resulting in the release of neurotransmitters into the synaptic cleft.

The release of these neurotransmitters allows them to bind to receptors on the postsynaptic neuron, carrying the signal forward and potentially generating a new nerve impulse in that neuron. This process is essential for transmitting signals across synapses, making neurotransmitter release a fundamental action in neuronal communication.