IGCSE Biology 8 Views 1 Answers
Explain the differences in composition between inspired and expired air
Explain the differences in composition between inspired and expired air
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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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