When we breathe in air, nitrogen (N2) makes up about 78% of the Earth's atmosphere. However, our bodies do not possess the ability to absorb nitrogen directly from the air we breathe. The nitrogen that we inhale and our bodies do not absorb is primarily exhaled back into the environment without undergoing any significant changes.
During the breathing process, oxygen is taken in and utilized by our cells for various metabolic processes. Oxygen is delivered to the tissues through the bloodstream, where it participates in cellular respiration to produce energy. Nitrogen, on the other hand, does not play a direct role in these metabolic processes.
The nitrogen that is inhaled along with oxygen enters our lungs and dissolves to some extent in the bloodstream. However, since our bodies do not have a specific mechanism to utilize nitrogen, it remains largely unchanged as it circulates through the body. As blood returns to the lungs for oxygenation, nitrogen is released from the bloodstream and exhaled out during the process of breathing.
In essence, the nitrogen that is not absorbed by our bodies follows a continuous cycle of inhalation and exhalation. It is not chemically altered or utilized in the same way as oxygen, carbon dioxide, or other essential gases that participate in metabolic reactions.