The primary function of the nervous system is to control the different systems of our body. The two parts into which our nervous system is divided are the central nervous system and peripheral nervous system. The spinal cord and brain together form the central nervous system.he primary function of the nervous system is to control the different systems of our body. The two parts into which our nervous system is divided are the central nervous system and peripheral nervous system. The spinal cord and brain together form the central nervous system.