IGCSE Biology 5 Views 1 Answers
Explain the differences in composition between inspired and expired air
Explain the differences in composition between inspired and expired air
Answer
The differences in composition between inspired (inhaled) air and expired (exhaled) air are significant due to the physiological processes that occur during respiration. Here’s a detailed comparison focusing on key components: oxygen, carbon dioxide, and water vapor.
1. Oxygen (O₂)
- Inspired Air: Contains approximately 21% oxygen.
- Expired Air: Contains about 16% oxygen.
- Difference: The decrease in oxygen content in expired air occurs because oxygen is absorbed by the body for cellular respiration, which is essential for energy production.
2. Carbon Dioxide (CO₂)
- Inspired Air: Contains about 0.04% carbon dioxide.
- Expired Air: Contains around 4% carbon dioxide.
- Difference: The increase in carbon dioxide in expired air results from its production during cellular metabolism. CO₂ is transported from the tissues to the lungs, where it is expelled during exhalation.
3. Water Vapor
- Inspired Air: Typically has a lower concentration of water vapor and can vary based on environmental conditions.
- Expired Air: Generally contains a higher concentration of water vapor due to moisture added from the respiratory tract and alveoli during inhalation.
- Difference: The increase in water vapor in expired air reflects the humidification process that occurs as air passes through the respiratory system.
Summary of Differences
| Component | Inspired Air | Expired Air | Key Difference |
|---|---|---|---|
| Oxygen (O₂) | 21% | 16% | Oxygen is used by the body during metabolism. |
| Carbon Dioxide (CO₂) | 0.04% | 4% | CO₂ increases due to metabolic waste from cells. |
| Water Vapor | Lower | Higher | Expired air contains moisture added from the lungs. |
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