Neurotransmitter

Neurotransmitters are endogenous chemicals that enable neurotransmission. They are a type of chemical messenger which transmits signals across a chemical synapse from one neuron (nerve cell) to another 'target' neuron, muscle cell, or gland cell. Neurotransmitters are released from synaptic vesicles in synapses into the synaptic cleft, where they are received by neurotransmitter receptors on the target cell. Many neurotransmitters are synthesized from simple and plentiful precursors such as amino acids, which are readily available and only require a small number of biosynthetic steps for conversion. Neurotransmitters are essential to the function of complex neural systems. The exact number of unique neurotransmitters in humans is unknown, but more than 200 have been identified.