Why do humans sweat NaCl?

Question

Why not H20? Why salt? And why do we even sweat?

Thanks!

Answer 1

Sweat is effectively blood plasma, with some of the proteins filtered out. The sweat glands take blood, and allow the liquid to filter through the walls of the capillaries. These filters are able to sort out the proteins, because they're fairly large, but Ca, K, Na, and Cl are too small to filter out easily (it can be done, it's just not worth it for the sweat glands). Since plasma contains lots of these ions, so does your sweat.

Also, it helps keep the ion concentration in the blood at a stable level. If the sweat glands filtered out these ions, so only H2O came out, your blood would lose water, and the concentrations of Na, Ca, K, and Cl (electrolytes) would increase. This is why you need electrolytes in your water if you are working out hard. You lose a lot of liquid through sweat, and if you replenish it with regular water, it will dilute the electrolytes in your blood, whereas sweating out pure H2O would concentrate them.

Answer 2

We sweat to cool our bodies off.
If we're too hot - the NaCl will cover our skin to lower its temperature. Salt is in sweat because it keeps the temperature of the liquid more stable... so if it was just water - it would evaporate right away... while salt allows it to slowly but surely cool you down and than evaporate.

Answer 3

First of all people do sweat H20.