eli5 Why does our body sweat out salt when we need it?

Question

Since sodium is so important to keep electrolytes up in our body why does our body sweat it out instead of just simply water?

In: Biology

Answer 1

**Fun fact**: our sweat is actually *less* salty than the fluid in our cells and blood. Our bodies do already reabsorb some of the electrolytes from our sweat so as not lose too much willy-nilly.

Typically fluid moves around to different compartments in our bodies by following salt (via electrolyte gradients made by salt pumps). The fluid follows the salt out of our sweat glands cells to the ducts, then our bodies re-absorb some of the salt back into the cells, leaving less-salty (hypotonic) fluid behind to evaporate and cool us down.

**Summary**: our sweat fluid follows salt out of our cells and into our sweat gland ducts; our cells then reabsorb some of the salt but not quite all of it.

* [https://en.wikipedia.org/wiki/Perspiration](https://en.wikipedia.org/wiki/Perspiration)
* [https://www.researchgate.net/figure/Mechanism-underlying-elevated-sodium-and-chloride-levels-in-the-sweat-of-CF-patients_fig3_263808741](https://www.researchgate.net/figure/Mechanism-underlying-elevated-sodium-and-chloride-levels-in-the-sweat-of-CF-patients_fig3_263808741)
* [https://pubmed.ncbi.nlm.nih.gov/31608304/](https://pubmed.ncbi.nlm.nih.gov/31608304/)
* [https://pubmed.ncbi.nlm.nih.gov/15158544/](https://pubmed.ncbi.nlm.nih.gov/15158544/)

Edit: added a summary section.