Library · Physiology
What fever is for
Make it clearer
Fever is not the body losing control. It is the hypothalamus, the part of the brain that acts as a thermostat, deliberately raising the number it defends, which is called the set point. And once that number is up, the body holds the higher temperature in a controlled way.
Who gives the order? Pyrogens, the substances that produce fever. Some come from outside, like bacteria and viruses, and those are the exogenous pyrogens. They make the body manufacture its own, the endogenous pyrogens, with names like interleukin 1 and tumor necrosis factor.
And that heat is neither free nor useless: raising core temperature is known to improve survival and help clear infections.
Think of it this way: the thermostat is not broken, someone turned the number up on purpose. Holding it there burns more energy, but what is gained in survival outweighs that cost.
In brief
In fever the hypothalamus raises the set point and the body sustains a controlled rise in core temperature.
The thermostat is not broken: someone turned the number up on purpose.
It is triggered by exogenous pyrogens such as bacteria and viruses, which stimulate endogenous pyrogens such as interleukin 1 and tumor necrosis factor.
That rise is known to improve survival and help clear infections.
It costs more energy, but the survival benefit outweighs that metabolic cost.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Fever, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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