The purpose of the central nervous system is to receive information from the sensory organs and process this information to initiate some type of effect. The central nervous system consists of the brain and spinal cord.
Sensory input comes from the different sensory modalities such as touch, sight and smell. Sensory receptors pick up this sensory input and transform it into a nerve impulse that travels along a sensory neuron. At the spinal cord, the impulse transfers to an interneuron. The central nervous system receives this input and decides the action the body should take in response. It then sends a response to motor neurons that attach to an effector organ or tissue.