Which cells secrete intrinsic factor, and what is its role?

Which cells secrete intrinsic factor, and what is its role?

• A. Chief cells; essential for vitamin B12 absorption
• B. G cells; stimulates acid secretion
• C. Parietal cells; intrinsic factor essential for vitamin B12 absorption
• D. Mucous neck cells; protects mucosa

Answer: (C)

Intrinsic factor is produced by parietal cells in the stomach. This glycoprotein binds vitamin B12 (cobalamin) and forms a complex that travels to the terminal ileum, where receptors take up the IF–B12 complex for absorption. Without intrinsic factor, vitamin B12 cannot be efficiently absorbed, leading to B12 deficiency and pernicious anemia. Parietal cells also secrete hydrochloric acid, but intrinsic factor’s critical job is enabling B12 uptake, not acid production. Other gastric cells have different roles: chief cells secrete pepsinogen, G cells secrete gastrin to stimulate acid, and mucous neck cells produce protective mucus.

Intrinsic factor is produced by parietal cells in the stomach. This glycoprotein binds vitamin B12 (cobalamin) and forms a complex that travels to the terminal ileum, where receptors take up the IF–B12 complex for absorption. Without intrinsic factor, vitamin B12 cannot be efficiently absorbed, leading to B12 deficiency and pernicious anemia. Parietal cells also secrete hydrochloric acid, but intrinsic factor’s critical job is enabling B12 uptake, not acid production. Other gastric cells have different roles: chief cells secrete pepsinogen, G cells secrete gastrin to stimulate acid, and mucous neck cells produce protective mucus.