What do our lungs exchange during breathing?

The lungs play a critical role in the process of respiration, where they are primarily responsible for the exchange of gases. During breathing, oxygen from the inhaled air enters the bloodstream in the lungs, while carbon dioxide, a waste product of cellular metabolism, is removed from the blood and exhaled. This exchange occurs in the alveoli, tiny air sacs in the lungs that have a rich blood supply.

The fundamental process can be described as oxygen being absorbed into the blood and carbon dioxide being expelled from the blood into the lungs for exhalation. This is vital for maintaining the body’s pH balance and ensuring that cells receive the oxygen they need for energy production. Thus, the accurate description of this essential physiological process is the exchange of carbon dioxide for oxygen.

The other options do not represent the fundamental exchange that occurs in the lungs during typical respiration. For instance, carbon monoxide is a dangerous gas that can interfere with oxygen transport but is not part of the normal respiratory exchange. Nitrogen, although a major component of the air we breathe, is largely inert and does not participate in gas exchange within the lungs under normal conditions.