The nervous system comprises the
(1) central nervous system (CNS) and
(2) peripheral nervous systems (PNS).
The central nervous system is composed of the brain and the spinal cord. This system controls behavior. All body sensations are sent by receptors to the central nervous system to be interpreted and acted upon. All nerve impulses that stimulate muscles to contract and glands to secrete substances get the message from the central nervous system. The peripheral nervous system is composed of nerves. This system is a pathway to and from internal organs. PNS serves as a pathway to the brain for the five senses and helps humans adjust to the world around them. The central nervous system includes the encephalon ( brain , brain stem ) and spinal cord; the peripheral system contains the body’s other nerves. Made of billions of interconnected nerve cells , the nervous system is a vast communication network linking all body parts and allowing us to interact with our environment