Which is true ?

Options

A. `PO_(2)` of deoxygenated blood is 95 mm hg
B. `Pco_(2)` of alveolar air is 40 mm Hg
C. `Pco_(2)` of oxygenated blood is 95 mm Hg
D. `Pco_(2)` of deoxygneated blood is 40 mm Hg

Answer

To determine which statement is true regarding the partial pressures of oxygen and carbon dioxide in the blood and alveolar air, we need to analyze the information provided in the video transcript step by step.

### Step-by-Step Solution:

1. **Understanding Partial Pressure of Gases**:
- The partial pressure of a gas is the pressure exerted by that gas in a mixture of gases. It is crucial for the movement of gases during respiration.

2. **Partial Pressure of Oxygen in Deoxygenated Blood**:
- The video states that the partial pressure of oxygen in deoxygenated blood is not 95 mm Hg. Instead, it is lower because deoxygenated blood has less oxygen. The correct value is around 40 mm Hg.

3. **Partial Pressure of Carbon Dioxide in Alveolar Air**:
- The transcript mentions that the partial pressure of carbon dioxide in alveolar air is 40 mm Hg. This is accurate and represents the normal value for carbon dioxide in the alveoli.

4. **Partial Pressure of Oxygen in Oxygenated Blood**:
- The oxygenated blood has a partial pressure of oxygen of 95 mm Hg, which is correct. This indicates that oxygenated blood is rich in oxygen.

5. **Partial Pressure of Carbon Dioxide in Oxygenated Blood**:
- The video clarifies that the partial pressure of carbon dioxide in oxygenated blood is not 95 mm Hg but rather around 40 mm Hg, as oxygenated blood has a lower concentration of carbon dioxide.

6. **Partial Pressure of Carbon Dioxide in Deoxygenated Blood**:
- The partial pressure of carbon dioxide in deoxygenated blood is higher than in oxygenated blood. The video states that it is approximately 45 mm Hg, indicating that deoxygenated blood has a higher concentration of carbon dioxide after gas exchange in the tissues.

### Conclusion:
Based on the analysis of the statements:
- The correct statement is: "The partial pressure of carbon dioxide of alveolar air is 40 mm Hg."