infections
Defenses Against Infection
Fever
Body temperature increases as a protective response to infection and injury. An elevated body temperature ( Fever in Adults ) enhances the body’s defense mechanisms, although it can cause discomfort. A part of the brain called the hypothalamus controls body temperature. Fever results from an actual resetting of the hypothalamus's thermostat. The body raises its temperature to a higher level by moving (shunting) blood from the skin surface to the interior of the body, thus reducing heat loss. Shivering (chills) may occur to increase heat production through muscle contraction. The body's efforts to conserve and produce heat continue until blood reaches the hypothalamus at the new, higher temperature. The new, higher temperature is then maintained. Later, when the thermostat is reset to its normal level, the body eliminates excess heat through sweating and shunting of blood to the skin. Certain people (such as the very old, the very young, and people with an alcohol use disorder) are less able to generate a fever. These people may experience a drop in temperature in response to severe infection. 