GED Science TestLife ScienceHard
A patient is diagnosed with a severe deficiency of intrinsic factor. Which of the following is the most likely consequence of this deficiency?
- AExcessive production of stomach acid, leading to ulcers.
- BImpaired digestion of fats, resulting in steatorrhea.
- CIncreased absorption of iron, leading to hemochromatosis.
- DReduced absorption of Vitamin B12, causing pernicious anemia.
Show answer & explanationAnswer & explanation
Correct answer: D. Reduced absorption of Vitamin B12, causing pernicious anemia.
Intrinsic factor is a glycoprotein produced by parietal cells in the stomach that is essential for the absorption of Vitamin B12 (cobalamin) in the small intestine. A deficiency of intrinsic factor directly leads to impaired B12 absorption, which can cause pernicious anemia, a type of megaloblastic anemia.
Why the other options are wrong
- A. Intrinsic factor is secreted by parietal cells, which also produce stomach acid, but its deficiency doesn't cause excessive acid production; rather, it often correlates with conditions that *reduce* acid production.
- B. Fat digestion relies on bile and pancreatic lipases, not intrinsic factor.
- C. Iron absorption is regulated by hepcidin and is not directly linked to intrinsic factor.
Intrinsic Factor Function
Intrinsic factor is a protein secreted by the parietal cells of the stomach, vital for the absorption of Vitamin B12 in the ileum (the final section of the small intestine).
- Produced by parietal cells in the stomach.
- Binds to Vitamin B12, protecting it from digestion.
- Facilitates B12 absorption in the ileum.
- Deficiency leads to pernicious anemia.
Memory trick: Intrinsic factor's missing, B12's fleeing, anemia's appearing!