The carbon dioxide is transported via blood to lungs mostly

Options

A. in combination with haemoglobin only
B. dissolved in blood plasma
C. in the form of bicarbontes
D. as carbaminohaemoglobin.

Answer

To answer the question regarding how carbon dioxide is transported via blood to the lungs mostly, we can break down the process into several steps:

### Step-by-Step Solution:

1. **Understanding Carbon Dioxide Transport**: Carbon dioxide (CO2) is a waste product produced by cells during metabolism and needs to be transported to the lungs for exhalation.

2. **Identifying the Main Transport Mechanisms**: There are three primary mechanisms by which carbon dioxide is transported in the blood:
- **Dissolved in Plasma**: About 7% of carbon dioxide is transported dissolved directly in the plasma.
- **Carbamino Compounds**: Approximately 23% of carbon dioxide binds to hemoglobin and other proteins to form carbamino compounds, primarily carbaminohemoglobin.
- **Bicarbonate Ions**: The majority, around 70%, is transported in the form of bicarbonate ions (HCO3-).

3. **The Role of Bicarbonate Formation**: In red blood cells (RBCs), carbon dioxide reacts with water to form carbonic acid (H2CO3) in the presence of the enzyme carbonic anhydrase. This carbonic acid then dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-).

4. **Conclusion**: Since 70% of carbon dioxide is transported as bicarbonate ions, this is the primary method of transport from the blood to the lungs.

5. **Final Answer**: Therefore, the carbon dioxide is transported via blood to the lungs mostly in the form of bicarbonates.