What is function of Intrinsic Factor?
**Core Concept**
The **intrinsic factor** is a glycoprotein produced by the **parietal cells** of the stomach, playing a crucial role in the absorption of **vitamin B12**. This process is essential for the production of **red blood cells** and the maintenance of the **nervous system**.
**Why the Correct Answer is Right**
The intrinsic factor binds to **vitamin B12** in food and facilitates its absorption in the **ileum** of the small intestine. This binding process is crucial because it allows the vitamin to be absorbed by the intestinal mucosa. The **intrinsic factor-vitamin B12 complex** then binds to a specific receptor on the surface of the intestinal cells, enabling the uptake of vitamin B12.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not specify the role of intrinsic factor.
**Option B:** Incorrect as it is not related to the function of intrinsic factor.
**Option C:** Incorrect because, although related to the stomach, it is not the function of intrinsic factor.
**Clinical Pearl / High-Yield Fact**
A deficiency in **intrinsic factor** can lead to **pernicious anemia**, a condition characterized by a lack of **red blood cells** due to insufficient **vitamin B12**.
**Correct Answer:** D. Intrinsic factor is necessary for the absorption of vitamin B12.