Synaptic Vesicles

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Synaptic vesicles, also called neurotransmitter vesicles, are filled with neurotransmitters, which they release into the synapse to communicate with other neurons:

• Vesicles are small, spherical organelles (subcellular structures), located in clusters inside terminal buttons (the transmitting ends of neurons), where they convert electrical signals (action potentials) from the terminal axon into chemical neurotransmitters.
• When an action potential reaches the presynaptic terminal, an influx of calcium causes the synaptic vesicles to fuse with the presynaptic membrane, releasing their neurotransmitter contents into the synaptic cleft.
• Neurons constantly recreate vesicles. The entire process of generating nerve impulses between neurons takes place in under 30 milliseconds, with new cell membrane bubbling into new vesicles within 100 milliseconds.