If air is made up of 78% Nitrogen, our blood uses Oxygen and we exhale Carbon dioxide, what happens to nitrogen?

Question

If air is made up of 78% Nitrogen, our blood uses Oxygen and we exhale Carbon dioxide, what happens to nitrogen?

In: Biology

Answer 1

All the nitrogen you breathe in just comes back out on the breath out. It doesn’t get absorbed, or released.

* The air you breathe in is ~78% nitrogen, ~21% oxygen, and ~1% other stuff.
* **The air you breathe out is ~78% nitrogen, still ~17% oxygen, only ~4% carbon dioxide**, and ~1% other stuff

As you can see, the mix we call “air” goes into the lungs, then *some* of the oxygen gets absorbed, some CO2 exits the blood into the lungs, and the nitrogen and other stuff just comes back out too.