Neurotransmitters

Chemicals that assist in the transfer of signals from one neuron to another. [Page 348]Neurotransmitters are stored in vesicles at the tips of axons (long, thin structures that extend from the cell body of neurons). When action potentials (see entry) reach the end of an axon, a neurotransmitter is released into the synapse (the tiny gap between neurons), where it spreads to the next cell. When they reach the membrane of the next (or postsynaptic) cell, the neurotransmitters bind to proteins called receptors. Neurotransmitters bind to their own receptors, but they do not bind to the receptors of other neurotransmitters. Each neurotransmitter can bind to several different types of receptors, and the neurotransmitter can have different effects depending on the type of receptor to which it binds. Dopamine, serotonin, and norepinephrine are examples of neurotransmitters. For more information, see Carlson (2007).