How do fevers form?


I know fevers are the body’s method of killing foreign bacteria and infections and such by raising the body’s temperature, but how exactly does it raise the body’s temperature?

In: 1

two primary methods. First, your blood vessels constrict, causing your body to retain heat in its core, drawing it away from the skin. This is in fact why you can both feel cold and feverish at the same time, your constricted blood vessels are limiting blood flow to the skin, where body heat is lost to convection to the air around you. Since there’s less blood flow to your skin, your natural body heat doesn’t go to the surface as much and be lost to exposure to normal elements

Secondly, muscle spasms (aka “shivering”) create muscle work, which burns calories and generates heat as a byproduct.

The shivery cold feeling you get while also having a fever is literally what’s causing the fever. Involuntary muscle use and vasoconstriction that’s preventing body heat loss

White blood cells send signals to the hypothalamus in your brain (your body’s thermostat), and the hypothalamus tells:

* Your blood vessels to start constricting, to reduce heat loss via the surface of your skin
* Your thyroid to start making hormones to increase your metabolism and produce more heat
* Your muscles to start shivering to also produce more heat

Infections trigger the immune system, leading to activation of immune cells, antibodies, and various other molecules. Some of these molecules are “pyrogens” (esp interleukin-1, interleukin-6, and TNF-alpha). These pyrogens act on the thermoregulatory center of the brain (in the hypothalamus) to raise the temperature setpoint (the temperature that the body tries to maintain). The body then raises its temperature by a variety of methods (eg increasing the BMR, decreasing sweating, constricting blood vessels that supply the skin, shivering). The higher temperature of the fever augments the function of the immune system, while stressing invading microorganisms. (Of course, too high a fever can be damaging).

When the infection subsides, the immune system deactivates, and the entire process runs in reverse to restore normal body temperature (eg, dilating blood vessels that supply the skin, increasing sweating).