Partial pressure of carbon dioxide in Alveoli , atmospheric air and tissues will be `:-`

Options

A. 0.3,40,45
B. 40,0.3,45
C. 0.3,104,28
D. 104,159,40

Answer

To determine the partial pressures of carbon dioxide (CO2) in the alveoli, atmospheric air, and tissues, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Partial Pressure**:
- Partial pressure refers to the pressure exerted by a single component of a mixture of gases. In this case, we are interested in the partial pressure of carbon dioxide in different environments: alveoli, atmospheric air, and tissues.

2. **Partial Pressure in Atmospheric Air**:
- The partial pressure of CO2 in atmospheric air is very low, approximately **0.3 mm Hg**. This is because the concentration of CO2 in the atmosphere is minimal compared to other gases like oxygen and nitrogen.

3. **Partial Pressure in Alveoli**:
- In the alveoli, the partial pressure of CO2 is around **40 mm Hg**. This is due to the exchange of gases during respiration, where CO2 from the blood diffuses into the alveoli.

4. **Partial Pressure in Tissues**:
- The partial pressure of CO2 in tissues is higher, approximately **45 mm Hg**. This is because tissues produce CO2 as a byproduct of metabolism, leading to a higher concentration of CO2 in the tissue spaces.

5. **Summarizing the Values**:
- Therefore, the partial pressures of carbon dioxide are:
- **Alveoli**: 40 mm Hg
- **Atmospheric Air**: 0.3 mm Hg
- **Tissues**: 45 mm Hg

### Final Answer:
- The partial pressures of carbon dioxide are:
- **Alveoli**: 40 mm Hg
- **Atmospheric Air**: 0.3 mm Hg
- **Tissues**: 45 mm Hg