The nervous system can be divided into 2 main part:
The central nervous system
Peripheral nervous system.
The Central Nervous System
The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers or axons, that connect the CNS to every other part of the body. 
The peripheral nervous system (PNS)
This is one of the two components of the nervous system, the other part is the central nervous system (CNS). The PNS consists of the nerves and ganglia outside the brain and spinal cord.
The main function of the PNS is to connect the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body.
Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins and mechanical injuries. 
The continuation of this topic would be discussed in the next post.
Thank you...