The process by which neurotransmitters are released into the synaptic cleft is called what?

The release of neurotransmitters into the synaptic cleft occurs through a process known as exocytosis. During exocytosis, vesicles containing neurotransmitters fuse with the presynaptic membrane of the neuron. This fusion is triggered by the influx of calcium ions that enter the neuron when an action potential arrives. Once the vesicles merge with the membrane, they release their contents into the synaptic cleft, allowing the neurotransmitters to diffuse across the gap and bind to receptors on the postsynaptic neuron.

This mechanism is crucial for synaptic transmission, as it enables communication between neurons. The specificity and timing of exocytosis ensure that neurotransmitters are released in response to neuronal activity, playing a vital role in functions such as muscle contraction, reflex actions, and overall nervous system signaling.

In contrast, endocytosis refers to the process by which cells internalize substances, reuptake pertains to the reabsorption of neurotransmitters by the presynaptic neuron after they have exerted their effect, and diffusion refers to the passive movement of molecules from an area of higher concentration to one of lower concentration, which is part of neurotransmitter movement but not the release process itself.