The document discusses the structure and function of the human nervous system. It describes the main components including the brain, spinal cord, and peripheral nervous system. The brain is divided into the cerebrum, cerebellum, and brain stem. The cerebrum is further divided into four lobes that control functions like movement, senses, vision, and hearing. The peripheral nervous system consists of cranial and spinal nerves that connect the central nervous system to the rest of the body and mediate both voluntary and involuntary functions.