presynaptic terminal
The endpoint of an axon containing synaptic vesicles and neurotransmitter release machinery.
Full Definition
The presynaptic terminal is the specialized ending of an axon that contains synaptic vesicles filled with neurotransmitters and the molecular machinery necessary for neurotransmitter release. Key components include voltage-gated calcium channels, SNARE proteins, and the active zone where vesicle fusion occurs. When an action potential reaches the terminal, calcium influx triggers vesicle exocytosis and neurotransmitter release into the synaptic cleft. The presynaptic terminal also contains mechanisms for vesicle recycling and neurotransmitter reuptake. Understanding presynaptic function is crucial for comprehending synaptic transmission and neurological disorders affecting neurotransmitter release.
Usage
Usage note: May be referred to as bouton in some contexts.
In Context
- "Calcium imaging revealed increased activity in the presynaptic terminal during stimulation." — Research methodology
- "The presynaptic terminal was enlarged in neurons from the transgenic mice." — Morphological analysis