Physiology--how the body detects pain stimuli.

Pain is the body's way of telling us something is wrong. It has a sensory and emotional component. This three-part series focuses on acute pain, describing the physiology of a normal and well-behaved pain pathway and how this relates to commonly used pain-management strategies. This first article introduces the pain system and how the body detects a threatening (noxious) stimulus. Part two describes how that pain message is transmitted to the spinal cord and the brain, and the response of the brain to the stimulus. The third article discusses the assessment of pain.