Book 1, Question 29
Why Do We Sweat? Your Built-In Cooling System!
Sweat is your body's natural cooling system. When you get hot, sweat comes out onto your skin from tiny sweat glands, and as the liquid evaporates into water vapor it carries heat away with it. A breeze helps the sweat evaporate faster, so you cool down more quickly. The page says your skin has about 2 to 4 million sweat glands working every day. Try running around and then standing in a breeze to test your hypothesis!
From the book
Page from A Million Whys Book 1
More fun facts
- A part of your brain called the hypothalamus is in charge of your temperature. When you get too hot, it tells your body to sweat.
- Sweat is almost all water, with tiny amounts of salt, sugar, ammonia, and urea.
- Sweat leaves your skin through tiny holes called pores.
- It is not the wetness that cools you. The evaporation of sweat is what chills your skin.
- Sweat first collects in tiny pools in your pores, then they join into a thin liquid film. That is how a few prickles turn into a soaked shirt.
- Sweat on its own does not really stink. The smell comes from bacteria on your skin mixing with it.
- When you sweat a lot, drink plenty of water so you do not get dehydrated.
Sources: KidsHealth (Nemours), Science News Explores
Questions kids ask
Why does sweat smell?
Bacteria living on your skin mix with the sweat and make the smell.
What is sweat made of?
Mostly water, plus tiny amounts of salt, sugar, ammonia, and urea.