The nervous system is a complex network that coordinates the body's responses to internal and external stimuli. It consists of two main parts: the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which connects the CNS to the rest of the body. Nervous system activity involves the transmission of electrical signals, known as nerve impulses, that allow communication between different body parts. When a stimulus is detected, sensory receptors send signals to the CNS, where the information is processed. The CNS then sends out responses through the PNS to muscles and glands, enabling actions such as movement or secretion. This intricate process ensures that the body can react quickly and effectively to changes in the environment.