Neurotransmitter

Neurotransmitters are chemicals that are used to relay, amplify and modulate electrical signals between a neuron and another cell. According to the dogma of the 1960's, a chemical can be classified as a neurotransmitter if it respects the following conditions:

Mechanism of action

Within the cells, small-molecule neurotransmitter molecules are usually packaged in vesicles. When an action potential travels to the synapse, the rapid depolarization causes calcium ion channels to open. Calcium then stimulates the transport of vesicles to the synaptic membrane; the vesicle and cell membrane fuse, leading to the release of the packaged neurotransmitter, a mechanism called exocytosis.

Related Topics:
Cells - Vesicle - Action potential - Membrane - Exocytosis

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The neurotransmitters then diffuse across the synaptic cleft to bind to receptors. The receptors are broadly classified into ionotropic and metabotropic receptors. Ionotropic receptors are ligand-gated ion channels that open or close through neurotransmitter binding. Metabotropic receptor, which can have a diverse range of effects on a cell, transduct the signal by second messenger systems.

Related Topics:
Diffuse - Receptor - Ionotropic - Metabotropic

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Neuroactive peptides are synthesized in the neuron's soma and are transported through the axon to the synapse. They are usually packaged into dense-core vesicles and are released through a similar, but metabolically distinct, form of exocytosis used for small-molecule synaptic vesicles.

Related Topics:
Soma - Axon

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