True or False: Is Atmospheric Air Composition the Same as Alveolar Air?
Question:
True or False: The composition of the air in the atmosphere and the composition of the air in the alveoli are exactly the same.
Answer: False
🧬 Detailed Explanation
🌬️ Atmospheric Air Composition
The air in our surrounding atmosphere contains the following gases:
- Nitrogen (N₂): ~78%
- Oxygen (O₂): ~21%
- Carbon Dioxide (CO₂): ~0.04%
- Water vapor & trace gases: Variable depending on climate and humidity
🫁 Alveolar Air Composition
When air enters the lungs, gas exchange occurs in the alveoli. This process alters the composition of the air as follows:
- Oxygen: Diffuses into the bloodstream, decreasing its concentration in alveolar air (~14%)
- Carbon Dioxide: Diffuses from blood into alveoli, increasing its concentration (~5-6%)
- Water Vapor: Alveolar air is fully saturated with moisture from the lung’s internal surface
🔄 Comparison Summary
- Alveolar air has less oxygen than atmospheric air.
- Alveolar air has more carbon dioxide than atmospheric air.
- Alveolar air is more humid than atmospheric air.
Conclusion: Due to the physiological gas exchange process in the lungs, the composition of air in the alveoli is not the same as that in the atmosphere.