Role of Prostaglandins in Fever and Temperature Regulation

Abstract

The remarkable ability of a warm-blooded animal to regulate its body temperature makes it relatively independent of the thermal conditions of the external environment. Every living organism produces heat which may be stored or given off to the environment. This condition allows an animal to reach a “steady state” of thermal exchange with its surroundings. In the homeothermic animal, heat production and heat loss are regulated to maintain internal body temperature within narrow limits over a wide range of environmental conditions. This thermohomeostasis is achieved in animals by two principal systems, namely behavioral and autonomic. In man these include regulation of heat loss, and of heat production. The heat loss regulation involves the choice of clothing, artificial environments, alterations in the skin blood flow, and variation in the level of evaporative heat loss by sweating. Heat production can be modified by altering the level of basal heat production by shivering or nonshivering thermogenesis, and by voluntary muscular activity. Deviations of about 2°C in central body temperature from the normal level, in general, do not seriously impair body function in man. Increases above this range can lead to convulsions, particularly in infants, and a further increase may cause death. If body temperature falls below normal limits (hypothermia), nervous system function is depressed, leading to a loss of consciousness and impairment of thermoregulation itself. As temperature falls even further, the coordinated contraction of heart muscle is disrupted.