The oxygen that we breathe just does not comprise of oxygen. It also contains about 78 per cent of nitrogen, 21 per cent of oxygen and rest is a mixture of different gases such as argon etc. AS the air flows in to the lungs, there is an exchange of gases between the inhaled air and the blood vessels. The oxygen in the air diffuses into the blood and carbon dioxide in the blood is given off. The expelled or exhaled air has a higher concentration of carbon dioxide. The oxygen we breathe in is crucial to obtain energy for growth and sustenance. This makes us, like most other living beings on earth, aerobic or oxygen dependent. Organisms that can live in the absence of oxygen are called anaerobic.
Even if we did nothing but rest, we would need about 350 litres of oxygen everyday.
Even if we did nothing but rest, we would need about 350 litres of oxygen everyday.