What is the primary gas exchanged in the respiratory system?

The primary gas exchanged in the respiratory system is oxygen. During the process of respiration, oxygen is inhaled into the lungs, where it diffuses across the alveolar membranes into the bloodstream. This exchange is crucial for cellular function, as oxygen is needed for aerobic metabolism, which produces the energy necessary for cellular activities.

In the lungs, carbon dioxide, a waste product of metabolism, is simultaneously removed from the blood and exhaled. However, while carbon dioxide is important to monitor in respiratory function, the main purpose of breathing is to supply oxygen to the body and eliminate carbon dioxide. Nitrogen and helium are present in the air we breathe, but they are not involved in the gas exchange process; they do not participate in the metabolic processes that require oxygen and produce carbon dioxide.