The nervous system is a complex biological structure responsible for coordinating the body's rapid responses to internal and external stimuli. It comprises the brain, spinal cord, and network of peripheral nerves, which work together to process information, facilitate communication between different body parts, and regulate nearly all bodily functions. Basic functions include sensory input—receiving data from receptors throughout the body—followed by integration, where the central processing units interpret the data. This leads to motor output, which involves sending signals via motor neurons to effectors, such as muscles or glands, allowing for coordinated actions, maintaining homeostasis, and facilitating cognitive processes.