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This image is a derivative work of the following images: File:Synapse_diag1.png licensed with Cc-by-sa-3.0-migrated, GFDL . 2005-09-23T19:24:14Z Nrets 642x765 (172072 Bytes) Corrected errors from original version
The synaptic cleft—also called synaptic gap—is a gap between the pre- and postsynaptic cells that is about 20 nm (0.02 μ) wide. [12] The small volume of the cleft allows neurotransmitter concentration to be raised and lowered rapidly.
Furthermore, psychoactive drugs could potentially target many other synaptic signalling machinery components. In fact, numerous neurotransmitters are released by Na+-driven carriers and are subsequently removed from the synaptic cleft. By inhibiting such carriers, synaptic transmission is strengthened as the action of the transmitter is prolonged.
Chemical synaptic transmission is the transfer of neurotransmitters or neuropeptides from a presynaptic axon to a postsynaptic dendrite. [3] Unlike an electrical synapse, the chemical synapses are separated by a space called the synaptic cleft, typically measured between 15 and 25 nm. Transmission of an excitatory signal involves several steps ...
An axo-axonic synapse is a type of synapse, formed by one neuron projecting its axon terminals onto another neuron's axon. [1]Axo-axonic synapses have been found and described more recently than the other more familiar types of synapses, such as axo-dendritic synapses and axo-somatic synapses.
Calcium ion entry into the presynaptic terminal causes the presynaptic release of glutamate, which diffuses across the synaptic cleft, binding to glutamate receptors on the postsynaptic membrane. There are four subtypes of glutamate receptors : AMPA receptors (AMPARs) (formerly known as quisqualate receptors), NMDA receptors (NMDARs), kainate ...
About once every second in a resting junction randomly one of the synaptic vesicles fuses with the presynaptic neuron's cell membrane in a process mediated by SNARE proteins. Fusion results in the emptying of the vesicle's contents of 7000–10,000 acetylcholine molecules into the synaptic cleft, a process known as exocytosis. [6]
Normally, transporters in the synaptic membrane serve to remove neurotransmitters from the synaptic cleft and prevent their action or bring it to an end. However, on occasion transporters can work in reverse, transporting neurotransmitters into the synapse, allowing these neurotransmitters to bind to their receptors and exert their effect.