Pain

A localized sensation that can range from mild discomfort to an excruciating experience. Stimulation of sensory nerve endings called nociceptors in the skin leads to pain messages being sent to the brain. Some nociceptors respond only to severe stimulation, others to warning stimuli. Pain receptors are present in other structures, such as blood vessels and tendons. Pain that may be felt at a point some distance from the cause is known as referred pain. Treatment for pain may include drugs, electrical stimulation ( TENS), surgery, or therapies such as acupuncture. (See also pain relief, endorphins.)