Why couldn’t we just use a bag and reuse the air we breathe when underwater

Question

I’ve always wondered this since I was a child, and I see people use bags to rebreathe the air they have in their lungs for panic attacks, which only increases my curiosity.

In: Biology

Answer 1

When you breathe you take in oxygen. You use the oxygen in your cells and produce carbon dioxide as a waste product which you breathe out.

So without a supply of oxygen, you’ll use it all use in cellular chemical reactions and die as it runs out.