Identify the correct match.

Options

A. Atmospheric air : p`O_2`- 159 mm Hg, p`CO_2` - 3 mm Hg
B. Pulmonary artery : `PO_2 - 95` mm Hg , `pCO_2` -40 mm Hg
C. Alveolar air : `pO_2- 104` mm Hg, `pCO_2`- 40 mm Hg
D. Pulmonary vein :` pO_2 - 40 `mm Hg , `pCO_2`- 45 mm Hg

Answer

To solve the question of identifying the correct match regarding the partial pressures of gases in different locations of the respiratory system, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understand the Context**: We need to identify the correct match of partial pressures of oxygen (O2) and carbon dioxide (CO2) in different areas of the respiratory system.

2. **Evaluate Atmospheric Air**:
- The partial pressure of oxygen (O2) in atmospheric air is given as 159 mm of Hg. This is correct as it is close to the actual value (approximately 160 mm of Hg).
- The partial pressure of carbon dioxide (CO2) is given as 3 mm of Hg. However, the correct value should be around 0.3 mm of Hg. Therefore, this option is incorrect.

3. **Evaluate Pulmonary Artery**:
- The partial pressure of oxygen (O2) is given as 95 mm of Hg. This is incorrect; the correct value should be approximately 104 mm of Hg.
- The partial pressure of carbon dioxide (CO2) is given as 40 mm of Hg, which is correct. However, since the oxygen value is incorrect, this option is also not a correct match.

4. **Evaluate Alveolar Air**:
- The partial pressure of oxygen (O2) is given as 104 mm of Hg, which is correct.
- The partial pressure of carbon dioxide (CO2) is given as 40 mm of Hg, which is also correct. Therefore, this option is a correct match.

5. **Evaluate Pulmonary Vein**:
- The partial pressure of oxygen (O2) is given as 40 mm of Hg, which is incorrect; it should be around 104 mm of Hg.
- The partial pressure of carbon dioxide (CO2) is given as 45 mm of Hg, which is correct. However, since the oxygen value is incorrect, this option is not a correct match.

6. **Conclusion**: The only correct match is the one for alveolar air, where the partial pressures of oxygen and carbon dioxide are both provided correctly as 104 mm of Hg and 40 mm of Hg, respectively.

### Final Answer:
The correct match is the third option: **Alveolar Air - O2: 104 mm of Hg, CO2: 40 mm of Hg.**