Dopamine is one of a class of neurotransmitters known as catecholamines. A neurotransmitter is a chemical messenger released from a presynaptic nerve cell or neuron at its terminal into a synapse. A synapse is a narrow gap between the terminal of a presynaptic neuron's axon and a signal- receiving portion (dendrite or cell body) of another neuron or effector cell. The neurotransmitter is released from synaptic vescicles in the presynaptic neuron, diffuses across the synaptic cleft, binds to the postsynaptic cell and stimulates it. After stimulation, the neurotransmitter is removed from the synapse by enzyme action or cell uptake. There are different types of neurotransmitters including acetylcholine, biogenic amines, amino acids, and neuropeptides. Dopamine is one of the biogenic amines, neurotransmitters that are derived from amino acids, and is a member of the group called catecholamines that are derived from the amino acid, tyrosine. Dopamine is produced mainly...