How does the body produce salty sweat? — Joshua, Cebu, Philippines
Marshall Brain Answered:
You have millions of sweat glands covering your body. Each of them is able to produce tiny drops of moisture on your skin when your body overheats.
Where does the moisture come from? From blood plasma. Plasma is the watery liquid that remains after you filter red blood cells and platelets out of blood. Blood plasma is fairly salty (more than a teaspoon of salt per liter of blood). Since plasma is the source for sweat, the sweat is going to be salty. A sweat gland naturally tries to reclaim some of the salt leaving the body, but a good bit of it ends up getting released. If you are sweating a lot in dry air, it can even leave a salty dust on the skin. For more info see: How Sweat Works.