The nerve cell consists of four main parts (Chudler, 2002a):
1- Cell body.
The cell body contains a number of specialized structures required to maintain the cell, namely the nucleus. It is located in the middle and is spherical in shape. It contains genetic material (DNA). This acid determines the structure and function of the cell. In addition, the cell body is filled with a semi-liquid, colorless substance. It is called protoplasm and is completely covered by a cell wall that organizes everything that passes to and from it. There are also centers within the protoplasm that convert oxygen into energy and make protein. And chemicals called neurotransmitters, which play an important role in the transmission and communication process (Daoud, 2004).
2-Dendrites.
They are hairs that protrude from the body of the nerve cell and branch out and work to receive messages coming to the cell body.
3- Axon.
It branches off from the nerve cell and may reach several feet in length in some sensory cells and motor cells, and its function is to transmit instructions from the cell body to other nerve cells or to muscles and glands. Sometimes it is surrounded by a fatty covering called the myelin sheath, which acts as an insulator and is formed in colloidal cells. Cells that have this covering carry messages faster than those that do not contain it (Daoud, 2004). There are nodes in it called nodes of Ranvier. Ranvier (are structures on which the conduct of nerve impulses depends). The part confined between every two nodes is called the internode, and the amount of myelin increases. From birth until maturity, the fatty envelope is surrounded by Schwan cells or sheath of Schwann. These cells are believed to be the basis for the emergence of the fatty envelope and thus are a site of high energy (Ross, 1980).
4- Axon Terminals.
At the end of the axon there is a group of branches at the end of which are sacs containing neurotransmitters through which messages from the nerve cell pass (Daoud, 2004).