præsynaptisk

Præsynaptisk refers to the part of a synapse that is located on the side of the gap or cleft from which the nerve impulse is arriving. A synapse is the junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter. The præsynaptic neuron is the one that transmits the signal. It releases chemical messengers, called neurotransmitters, from its terminal boutons into the synaptic cleft. These neurotransmitters then bind to receptors on the postsynaptic neuron, which is the cell that receives the signal. The præsynaptic terminal contains vesicles filled with neurotransmitters. When an action potential reaches the præsynaptic terminal, it triggers the influx of calcium ions. This influx of calcium causes the vesicles to fuse with the præsynaptic membrane and release their neurotransmitter contents into the synaptic cleft. Therefore, the præsynaptic component is crucial for the transmission of information between neurons.