The nervous system consists of the central nervous system (brain and spinal cord) and peripheral nervous system (cranial and spinal nerves). The central nervous system processes sensory information and sends motor commands to the body. The peripheral nervous system carries sensory information to the central nervous system and motor commands from it to the muscles and glands. The document then discusses two suffixes: -plegia, meaning paralysis, and -ataxia, meaning disorder. It provides paraplegia and ataxia as examples, describing their symptoms which result from damage to different parts of the central nervous system.