The respiratory membranes facilitates the exchange of respiratory gases through diffusion . Oxygen enters the deoxygenated blood through diffusion because `:-`

Options

A. Partial pressure of oxygen in alveolar air and capillaries is 40mm Hg and 100 mm Hg respectively
B. Partial pressure of oxygen in alveolar air and capillaries is 100 mm Hg and 40mm Hg respectively
C. Partial pressure of oxygen in alveolar air and capillaries is 46mm Hg and 40mm Hg respectively
D. Partial pressure of oxygen of alveolar air and capillaries it 40mm Hg and 46 mm Hg respectively

Answer

**Step-by-Step Solution:**

1. **Understanding the Concept of Partial Pressure**:
- Gaseous exchange in the respiratory system occurs due to differences in partial pressures of gases. The gas will naturally move from an area of higher partial pressure to an area of lower partial pressure.

2. **Identifying the Partial Pressures**:
- In the alveoli, the partial pressure of oxygen (pO2) is higher than in the deoxygenated blood (capillaries). For example, the pO2 in the alveoli can be around 100 mm Hg, while in the capillaries, it can be around 40 mm Hg.

3. **Diffusion Process**:
- Since the partial pressure of oxygen is higher in the alveoli (100 mm Hg) compared to the capillary blood (40 mm Hg), oxygen will diffuse from the alveoli into the blood.

4. **Examining the Role of Carbon Dioxide**:
- Conversely, carbon dioxide (CO2) has a higher partial pressure in the blood (around 46 mm Hg) compared to the alveoli (around 40 mm Hg). Therefore, CO2 will diffuse from the blood into the alveoli.

5. **Conclusion**:
- The oxygen enters the deoxygenated blood through diffusion because the partial pressure of oxygen is higher in the alveoli than in the deoxygenated blood, facilitating the movement of oxygen into the blood.

**Final Answer**: Oxygen enters the deoxygenated blood through diffusion because the partial pressure of oxygen in the alveoli is higher than that in the deoxygenated blood.

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