Library · Physiology
Sweating
Make it clearer
Sweating is how the body moves heat out, and it is not up to you: it is driven by the thermoregulatory center of the hypothalamus, a region deep in the brain that acts as a thermostat. The exact part that does this is called the preoptic area.
The signal comes from thermoreceptors, the body's temperature sensors. When they report that temperature is rising, the hypothalamus switches on certain nerve fibers of the sympathetic system, the ones called cholinergic, that run straight to the sweat glands. Those glands are what secrete sweat.
And here is the detail almost no one thinks about: what cools you is not sweat wetting the skin, it is the moment the water turns into vapor. Each gram of water evaporated carries away 0.58 kilocalories, and about 22% of the heat the body loses goes out by that route.
In brief
Sweating is how the body loses heat by evaporating water, and it is driven by the thermoregulatory center of the hypothalamus, in the preoptic area.
When thermoreceptors signal that temperature is rising, the hypothalamus activates sympathetic cholinergic fibers that supply the sweat glands.
Evaporating sweat removes about 22% of the heat the body loses, and each gram of water evaporated carries away 0.58 kilocalories.
What cools you is not the sweat on your skin but the water turning into vapor.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Temperature Regulation, StatPearlsPublished
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