Which of the following is correct about the transport of carbon dioxide from the tissue to lung alveoli ?

Options

A. `{:("Carbomino - Hb form","As Dissolved plasma","As Bicarbonate"),(20-25%,70%,5-7%):}`
B. `{:("Carbomino - Hb form","As Dissolved plasma","As Bicarbonate"),(70%,5-7%,20-25%):}`
C. `{:("Carbomino - Hb form","As Dissolved plasma","As Bicarbonate"),(5-7%,20-25%,70%):}`
D. `{:("Carbomino - Hb form","As Dissolved plasma","As Bicarbonate"),(20-25%,5-7%,70%):}`

Answer

To determine the correct statement about the transport of carbon dioxide (CO2) from tissues to lung alveoli, we need to understand the different methods by which CO2 is transported in the blood. Here’s a step-by-step breakdown of the transport mechanisms:

### Step 1: Identify the Methods of CO2 Transport
Carbon dioxide is transported in the blood through three primary mechanisms:
1. **Carbaminohemoglobin Formation**: CO2 binds to hemoglobin in red blood cells (RBCs) to form carbaminohemoglobin. This accounts for about 20-25% of CO2 transport.
2. **Dissolved CO2 in Plasma**: A small percentage (about 7%) of CO2 is transported dissolved directly in the plasma.
3. **Bicarbonate Ion Formation**: The majority (approximately 70%) of CO2 is converted into bicarbonate ions (HCO3-) in the blood.

### Step 2: Analyze the Options
Now, let’s evaluate the options provided in the question based on the information above:

- **Option A**: States that carbaminohemoglobin carries 20-25% of CO2. This is correct.
- **Option B**: Claims that carbaminohemoglobin forms 70% of CO2 transport. This is incorrect.
- **Option C**: States that carbaminohemoglobin accounts for 5-7% of CO2 transport. This is incorrect.
- **Option D**: Asserts that carbaminohemoglobin carries 20-25%, dissolved form 5-7%, and bicarbonate 70%. This is correct.

### Step 3: Conclusion
Based on the analysis, the correct option regarding the transport of carbon dioxide from tissues to lung alveoli is **Option D**.