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Whoo, what a great dodgeball game, Squeaks.  You must have been practicing your dodging.  Oh, boy, am I sweaty, which makes sense.  When your body gets too hot like from the temperature outside or from exercise, that makes you sweat.  Sweating is when your body lets out little droplets of liquid through your skin.  Even if it makes you feel kind of sticky and gross, sweat can be a good sign that your body is doing its job.  It's how you keep your temperature down.

Human bodies work best around 37 degrees Celsius, or 98.6 degrees Fahrenheit.  If your brain notices that your body is getting warmer, it sends a message to your sweat glands and tells them that you need to sweat.  Sweat glands are long coiled up tubes that are in the dermis layer of your skin, a little bit under the surface.  The sweat is made in the dermis, then leaves your body through tiny openings called pores.  You can sometimes see these pores if you look really closely at your skin.  When the sweat dries or evaporates into the air, some of the heat from your body escapes into the air, too, which helps you cool off.  

You can try it right now for yourself if you want.  Just splash a little water onto your arm.  Even if the water isn't cold, you'll start to feel your arm get colder as the water dries off.  We each have around 3 million sweat glands.  Most of them are called eccrine sweat glands, which are all over most of your body, especially on the palms of your hands, the bottoms of your feet, and your forehead.  You also have about 2000 apocrine glands, which are in places like your armpits, but they won't start sweating until you get a little older.

Your eccrine glands are the ones that get excited when your brain senses your body temperature getting too high, like when you're playing dodgeball, for example.  They're also connected to signals from your emotions in addition to your body temperature.  So if you're about to do something that makes you nervous, like getting up and making a speech, that might make you sweat, too.  The sweat released by the eccrine glands is made mostly of water, with very small amounts of other chemicals mixed in.  Those other chemicals are why sweat tastes salty.

Some people don't sweat much, and some people sweat a lot.  It can depend on lots of different things, including how big your body is, how used to exercise you are, and just differences between people.  Some very sweaty adults can produce up to two or three liters of sweat per hour, and humans are the sweatiest animals around.  Lots of animals sweat, but most don't produce large amounts of sweat to keep them cool the way that we do. 

Some animals, like dogs, stay cool by panting instead, which helps water evaporate out of their mouths.  A very long time ago, when humans were just getting started, they were developing big brains and living out in the open under the Sun, and having more sweat glands than other animals helped keep their bodies and their big brains nice and cool.

You sweat at least a little bit every day, even if you haven't exercised or gotten too hot, and even if you don't feel like you're sweating, it just means it's drying off before you notice it, and if you are sweating enough to notice it, it's extra important to make sure you're making up for it by drinking plenty of water.  Our bodies need lots of water to work properly and you lose some of that water when you sweat.  

So sweating might not always feel comfortable, but it means your body is doing a good job of keeping you cool and that it's time to drink some water and hit the showers.  You first, Squeaks. 

Thanks for joining us.  Do you have any questions about sweating or how our bodies work or anything at all?  We have a website where you can send them to us.  Just ask a grown-up to help you go to Patreon.com/SciShowKids to check it out.  Thanks, and we'll see you next time here at the Fort.

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