Intrinsic factor of castle is secreted by:

Appeared in: AIIMS Nagpur NO- 2020

Explanation

Parietal cells, also known as oxyntic cells, are located in the gastric glands of the stomach and are responsible for secreting intrinsic factor.
Intrinsic factor is a crucial glycoprotein that binds to vitamin B12, enabling its absorption in the terminal ileum.
A deficiency in intrinsic factor leads to the inability to absorb vitamin B12, resulting in a condition known as pernicious anemia.

Option A: Mucus cells secrete mucus, which forms a protective barrier for the stomach lining against acid and pepsin. They do not secrete intrinsic factor.
Option B: Chief cells are responsible for secreting pepsinogen, the inactive precursor of the enzyme pepsin, which digests proteins. They are not involved in vitamin B12 absorption.
Option D: B cells are lymphocytes, a type of white blood cell, that are central to the humoral immunity of the adaptive immune system. They have no role in gastric secretion.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of Gastric Secretions as background academic context rather than a clinical decision trigger.
Understanding that parietal cells secrete intrinsic factor is crucial for nurses, as damage to these cells (e.g., from chronic gastritis, gastrectomy) leads to pernicious anemia. Patients will require lifelong vitamin B12 injections because oral supplements cannot be absorbed.
Nurses should monitor for signs of vitamin B12 deficiency, such as fatigue, pallor, weakness, and neurological symptoms (e.g., tingling in hands and feet, balance problems), in patients with a history of gastric surgery or atrophic gastritis.
What if? If a patient undergoes a total gastrectomy (complete removal of the stomach), they lose all parietal cells. Consequently, they have zero production of intrinsic factor and will be unable to absorb dietary vitamin B12, necessitating lifelong parenteral (non-oral) B12 supplementation.

How to Approach the Question

First, identify the key term in the question: 'Intrinsic factor of Castle'.
Recall the different types of secretory cells located in the stomach lining and their primary functions.
Associate 'Parietal cells' with their two main products: hydrochloric acid (HCl) and intrinsic factor.
Differentiate this from 'Chief cells', which produce pepsinogen for protein digestion, and 'Mucus cells', which produce a protective mucus layer.
Eliminate 'B cells' as they are components of the immune system and are not involved in gastric digestion.
Conclude that parietal cells are the correct source of intrinsic factor.

Concept Tested & Keywords

QGHk0_1eNRgZSNfjdA7Ucb

E6 Histology Inderbir 11e p. 38-40

E6 Pharmacology Nursing Lilley 11e Part 3 p. 162-164

E6 Physiology Guyton 4SAE Part 2A p. 168-170

Practise the full AIIMS Nagpur NO- 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.