eli5 how do our bodies produce so much phlegm?

Question

I’m currently sick and my sinuses are draining so freaking much. How can my head contain so much snot? It’s never ending 🤢🤢.

In: 6

Answer 1

Snot is only about 1% salt and another 1% proteins. The other 98% is just water! The water is drawn directly out of your blood (which you should be replenishing by drinking plenty of fluids) so it can be rapidly and as you said seemingly endlessly replenished. Similarly the salt comes from the blood which is slightly salty as well. Since your mucus glands only need to contribute the 1% protein they can rapidly produce snot without being easily depleted.