What occurs when synaptic vesicles are electrically stimulated by a nerve impulse?

When synaptic vesicles are electrically stimulated by a nerve impulse, they undergo a process known as exocytosis. This involves the vesicles moving to the presynaptic membrane and fusing with it, allowing the contents to be released into the synaptic cleft. In many neurons, particularly those at neuromuscular junctions or in certain autonomic pathways, the neurotransmitter released is acetylcholine.

Once released into the synaptic cleft, acetylcholine then binds to receptors on the postsynaptic membrane, which triggers a response in the target cell. This communication is crucial for propagating signals across synapses, which is essential for muscle contraction and various neuronal functions.

While serotonin, dopamine, and norepinephrine are important neurotransmitters, they are not the primary neurotransmitter released during this process in most of the common synaptic environments where acetylcholine is involved. Thus, the release of acetylcholine accurately represents the key function of synaptic vesicle activation in response to a nerve impulse.