The document discusses the structure and function of the nervous system. It describes the central nervous system as consisting of the brain and spinal cord which act as the body's control center. The peripheral nervous system is made up of nerves connecting the central nervous system to the rest of the body. Within the central nervous system, neurons transmit electrical signals through the body to coordinate its activities. The three main sections of the brain are the cerebrum, cerebellum and brainstem, each with distinct roles in movement, coordination, memory and other cognitive functions.