The autonomic division is in turn divided into the sympathetic and parasympathetic divisions. The neuron , or nerve cell, is the basic functional unit of the nervous system. It is usually small compared to the rest of the neuron. One or more dendrites extend like tendrils from the cell body. The dendrites serve to receive incoming electrical signals from other neurons.
Most neurons have a single axon to transmit outgoing signals.
Axons vary in length from micrometers to over a meter. Portions of the axon are insulated by supporting cells with myelin , a phospolipid membrane. Neurons carry information from one end of the cell to the other by generating and propagating electrical signals. The potential difference across the neuron cell membrane is the basis for generating electrical signals. Much like a battery, this potential is creating by the uneven distribution of ions on either side of the membrane.