The Body's Defenses Against Pain
The body has internal mechanisms that help to control pain and its perception: endorphins and inhibition of pain transmission.
Naturally occurring analgesics called endorphins are produced by the body. These endorphins are produced by the brain and spinal cord and are many times stronger than morphine. However, they are safe and occur naturally in the body as a result of exercise and certain other stimulation. They serve to kill pain and to elevate the patient's mood level Endorphin production is increased with acute pain but decreases or stops as pain becomes chronic. Some authorities believe that activities other than exercise, such as laughter, also increase endorphin production. It is also believed that intake of certain chemicals and foods, including caffeine, nicotine, alcohol, salt, and sugar decrease endorphin production in all people, whether they are in pain or not.
Another internal mechanism for pain control is referred to as inhibition of pain transmission and works on what is called the gate control theory of pain. The theory maintains that small-diameter nerve fibers conduct pain stimuli toward the brain, but large-diameter nerve fibers inhibit the pain impulses. When too many stimuli are sent, certain cells in the spinal column interrupt the transmission as if closing a gate. Certain nursing measures for pain relief are based on the gate control theory.