What is true about diffusion capacity.

Options

A. Diffusion capactiy of `CO_` is much higher than `CO_(2)`
B. Diffusion capacity of `O_(2` is much higher than `CO_(2)`
C. Diffusion capacity of `O_(2)` and `CO_(2)` is same
D. None of the above

Answer

To answer the question "What is true about diffusion capacity?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand Diffusion Capacity**:
- Diffusion capacity refers to the measurement of the rate at which gases transfer from the alveoli (air sacs in the lungs) to hemoglobin in the capillaries.

2. **Identify the Gases Involved**:
- The gases we are considering in this context are carbon monoxide (CO), carbon dioxide (CO2), and oxygen (O2).

3. **Compare the Diffusion Capacities**:
- It is known that carbon monoxide has a much higher diffusion capacity compared to carbon dioxide and oxygen. This means that CO diffuses more readily from the alveoli into the blood than CO2 or O2.
- Oxygen has the lowest diffusion capacity among these gases.

4. **Evaluate the Options**:
- **Option 1**: "Diffusion capacity of carbon monoxide is much higher than carbon dioxide." - This statement is true.
- **Option 2**: "Diffusion capacity of oxygen is much higher than carbon dioxide." - This statement is false; oxygen has the lowest diffusion capacity.
- **Option 3**: "Diffusion capacity of oxygen and carbon dioxide is the same." - This statement is also false; they differ in their diffusion capacities.
- **Option 4**: "None of the above." - This statement is false since option 1 is true.

5. **Conclusion**:
- The correct answer is **Option 1**: "Diffusion capacity of carbon monoxide is much higher than carbon dioxide."