Neurons

About the Neurons

Neurons are the electrically excitable cells that carry information through the nervous system. A typical neuron has a cell body containing the nucleus, branching dendrites that receive input from other cells, and a single axon that carries output signals, sometimes over very long distances. Signals travel along the axon as action potentials, rapid changes in membrane voltage produced by the opening and closing of sodium and potassium channels, and many axons are wrapped in myelin, which greatly speeds conduction. At synapses, neurons release neurotransmitters such as glutamate, GABA, dopamine, serotonin, and acetylcholine that act on receptors of the next cell. Neurons are broadly classed as sensory neurons, motor neurons, and interneurons. The neuron doctrine, the idea that the nervous system is made of discrete cells, was championed by Santiago Ramon y Cajal, who shared the 1906 Nobel Prize with Camillo Golgi. Most neurons do not divide after development, which is one reason brain and spinal cord injuries are so difficult to repair.