Which gas is primarily exchanged in the alveoli of the lungs?

The gas that is primarily exchanged in the alveoli of the lungs is oxygen. The alveoli are tiny air sacs within the lungs where the exchange of gases takes place. When we inhale, oxygen-rich air enters the alveoli, and oxygen then diffuses through the alveolar walls into the blood in the surrounding capillaries. Simultaneously, carbon dioxide, which is a waste product produced by cells during metabolism, diffuses from the blood into the alveoli to be exhaled.

While carbon dioxide is certainly a crucial part of the gas exchange process, the primary purpose of this exchange mechanism is to supply oxygen to the bloodstream. Nitrogen and hydrogen are not involved in the primary gas exchange process in the lungs. Nitrogen makes up a significant portion of the air we breathe, but it is not utilized by the body in the same way that oxygen is. Hydrogen is not a significant component of the respiratory process. Thus, the focus of gas exchange in the alveoli is mainly on oxygen and carbon dioxide, with oxygen being the essential gas increased in the bloodstream to support cellular functions.