Which are the gases present in inhaled and exhaled air? What is the importance of them?

Question

Which are the gases present in inhaled and exhaled air? What is the importance of them?

Answer 1

What we breathe in is far from pure oxygen, but roughly by volume 78 per cent nitrogen, 21 per cent oxygen, 0.965 per cent argon and 0.04 per cent carbon dioxide (plus some helium, water and other gases). The permanent gases in air we exhale are roughly 78 per cent nitrogen, 15 to 18 per cent oxygen (we retain only a small amount), 4 to 5 per cent carbon dioxide and 0.96 per cent argon, the CO2 being of course used by plants during photosynthesis.

We only use use up a little oxygen on what we actually breathe, and what we exhale, CO2 increases. And the other gases we breathe just goes in and out of our system.

Answer 2

Inhaled air contains:  

more oxygen used to create energy

less carbon dioxide than…

Exhaled air which contains:  

more carbon dioxide produced as a waste product of energy production

less oxygen as it has been used in respiration

Inhaled air brings purity inside the system whereas the exhaled one takes out the impurity toxins (if any)