Nerve Fibers

Two kinds of nerve fibers, called "dendrites" and "axons," extend from the cell bodies of most neurons. Although a neuron usually has many dendrites, it has a single axon. In most neurons, the dendrites are relatively short and highly branched. These processes, together with the membrane of the cell body, provide the main receptive surfaces of the neuron to which processes from other neurons communicate. Often the dendrites have tiny, thornlike spines on their surfaces, which serve as contact points for parts of other neurons. The axon, which usually arises from a slight elevation of the cell body (axon hillock), is a slender, cyclindrical process with a nearly smooth surface and uniform diameter. This cable is a one-way pipe from one nerve cell to the axon terminal. Each nerve cell has a single axon, but the axon may have several branches (collaterals). The axon terminal is a point where the electrical charge sent from one nerve cell to another is changed into a chemical signal to be sent away from the region of the cell body.