Nervous system involves transmission of impulses from the receptors to the effector cells. it involves the detection of the stimuli by the receptor cells (includes the skin,eyes,mouth), then the stimuli is carried by the sensory neurone (joins the receptor cells and the spinal cord) to the central nervous system (the spinal cord), then the impulse is picked by the relay neurone and taken to the brain for processing, where the brain interprates the stimuli and sends a response. then the relay neurone from the brain joins to the motor neurone which connects the brain and the effector cells. The motor neurone carries the message to the effector cells (muscles and the glands), and finally a response is experienced in the specific place of the body by either movement of body muscles or secretions by the glands.