Four major organ systems are involved in wound healing: the sympathetic nervous system, the endocrine organs, the cardiovascular system, and an acute phase reaction involving the liver. During the immediate systemic response, the wounded person becomes alert, opium-like substances are released to decrease pain, the heart and respiratory rates quicken, blood glucose levels rise, and the basal metabolic rate speeds up. This is a stress reaction, with organ systems functioning at supraphysiological levels. A sustained level of stress takes a toll on the body's physiology unless supported by appropriate nutritional therapy.
The systemic response is produced as local chemical mediators spill into blood vessels from the wound. They activate circulating monocytes (a kind of immune cell) to release chemical messengers called cytokines. These cytokines cause the various metabolic changes seen after trauma. In cases of major trauma, there may be generalized fever; increased oxygen consumption; and increased metabolism of fats, glucose, and proteins.
As the reaction is prolonged over days or weeks, local lymph nodes and the spleen enlarge to supply immune cells.