0.044
Explanation
Breathing is the process of pulmonary ventilation involving the intake of atmospheric air and the expulsion of alveolar air. This process facilitates gas exchange, where oxygen is absorbed into the bloodstream and carbon dioxide, a metabolic waste product, is released from the blood into the lungs to be exhaled.
Analysis of Respiratory Gas Composition
The composition of air changes significantly between inhalation and exhalation due to cellular respiration:
- Carbon Dioxide ($CO_2$): Atmospheric air (inhaled) contains approximately 0.03–0.04% carbon dioxide. In contrast, exhaled air contains approximately 4.4% carbon dioxide, reflecting the elimination of metabolic waste.
- Oxygen ($O_2$): Inhaled air contains about 21% oxygen. Exhaled air contains roughly 16.4% oxygen, as the body utilizes a portion of it.
- Nitrogen ($N_2$): Nitrogen is physiologically inert in this context; its concentration remains largely unchanged at approximately 78% in both inhaled and exhaled air.
Key Takeaway: Exhaled air contains approximately 4.4% carbon dioxide, which is significantly higher than the 0.04% found in inhaled air.