Question

Explain the sequence of physiological events leading to fever.

Answer 1

Fever is caused by chemicals known as pyrogens, flowing in the bloodstream.

Normally, pyrogens help the immune system by fighting infectious agents, such as bacteria and viruses-- which are sensitive to temperature changes.

Pyrogens induce host cells, such as leukocytes and macrophages, to release fever-producing mediators called endogenous pyrogens (for example, interleukin-1). The phagocytosis of bacteria and breakdown products of bacteria present in the blood lead to the release of endogenous pyrogens into the circulation. These endogenous pyrogens are thought to increase the set point of the hypothalamic thermoregulatory center through the action of prostaglandin E2. In response to the sudden increase in set point, the hypothalamus initiates heat production behaviors (shivering and vasoconstriction) that raise the core body temperature to the new set point, establishing fever.