Largest fraction of CO2 is present in blood as:
**Core Concept**
The transport of carbon dioxide in the blood involves several mechanisms, with the majority being carried in a non-ionized form. This is due to the buffering capacity of the blood and the need to maintain acid-base balance.
**Why the Correct Answer is Right**
The largest fraction of CO2 is present in the blood as a non-ionized form, which is approximately 7-8%. This is because non-ionized CO2 can easily diffuse across the lipid bilayer of red blood cells and is transported in the blood as dissolved gas. The non-ionized form of CO2 is also more soluble in plasma than in red blood cells. The bicarbonate ion (HCO3-) is the primary ionized form of CO2 in the blood, making up around 60-70% of the total CO2 content.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot explain why it is incorrect.
* **Option B:** This option is also not provided, so we cannot explain why it is incorrect.
* **Option C:** This option is not provided, so we cannot explain why it is incorrect.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the transport of CO2 in the blood is a critical aspect of acid-base balance. The majority of CO2 is carried as a non-ionized form, which can easily diffuse across cell membranes, whereas the bicarbonate ion (HCO3-) is the primary ionized form of CO2 in the blood.
**Correct Answer:** C.