The nervous system is divided into the central nervous system and the peripheral nervous system. The central nervous system includes the brain and spinal cord, and controls and coordinates body functions. The peripheral nervous system connects the central nervous system to the rest of the body using nerves and contains sensory neurons that carry messages to the central nervous system and motor neurons that carry messages away from it. Neurons are the basic functional units of the nervous system and communicate with each other via electrical and chemical signals to control bodily functions like movement and organ activity.