O Level Biology 7 Views 1 Answers
Investigate and explain the differences between inspired and expired air
Investigate and explain the differences between inspired and expired air
Answered step-by-step
Inspired air and expired air differ significantly in their composition due to the processes of respiration and gas exchange that occur in the lungs. Here are the key differences:
Composition Differences
| Gas | Inspired Air (Inhaled) | Expired Air (Exhaled) |
|---|---|---|
| Oxygen (O₂) | Approximately 21% | Approximately 16% |
| Carbon Dioxide (CO₂) | Approximately 0.04% | Approximately 4% |
| Water Vapor | Lower concentration | Higher concentration |
| Nitrogen (N₂) | Approximately 78% | Approximately 78% |
Key Points
- Oxygen Content: Inspired air contains a higher percentage of oxygen (around 21%) compared to expired air, which has about 16%. This decrease occurs because oxygen is absorbed into the bloodstream during gas exchange in the alveoli.
- Carbon Dioxide Content: Expired air has a significantly higher concentration of carbon dioxide (around 4%) than inspired air, which contains only about 0.04%. This increase is due to carbon dioxide being a byproduct of cellular respiration, which diffuses from the blood into the alveoli to be exhaled.
- Water Vapor: Expired air typically has a higher concentration of water vapor compared to inspired air. The moisture in expired air results from the humidification of air in the lungs and the body’s temperature, which is around 37°C.
- Temperature: The temperature of expired air is generally warmer than that of inspired air, as it is exhaled at body temperature after being warmed in the respiratory tract.
These differences highlight the efficiency of the respiratory system in facilitating gas exchange, ensuring that oxygen is delivered to the bloodstream while carbon dioxide is removed from it.
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