The peripheral nervous system derives from cells next to the neural groove called the neural crest. Nerve tissue is distributed throughout the body in a complex integrated communications network. Neurons do the actual message transmission and integration while other nervous tissue cells called glial cells assist neurons by support, protection, defense and nutrition of the neurons. There are about 10 times more glial cells than neurons in the brain. Glial cells create the microenvironment needed for neuronal function and sometimes they assist in neural processing and activity.
Neurons are excitable cells.
This means that when properly stimulated, an action potential can be initiated that may be propogated over the cell membrane to transmit information to distant cells. Neurons are independent functional units responsible for the reception, transmission and processing of stimuli. The axon usually branches at its distal end and each branch terminating on another cell has a bulbous end. The interaction of the end bulb with the adjacent cell forms a structure called a synapse. Synapses are specialized to receive a signal and convert it into an electrical potential.