Pepsinogen enzyme is secreted by?

Appeared in: AIIMS Rishikesh & Jodhpur NO - 2017

Explanation

Chief cells, also known as peptic or zymogenic cells, are located in the gastric glands of the stomach.
These cells synthesize and secrete pepsinogen, which is the inactive precursor (proenzyme) of the protein-digesting enzyme, pepsin.
They also secrete gastric lipase, an enzyme that begins the digestion of fats.
The release of pepsinogen is stimulated by signals like acetylcholine from the vagus nerve and the presence of acid in the stomach.

Option B: Mast cells are immune cells found in connective tissues throughout the body, including the stomach lining. They release histamine and other mediators during inflammatory and allergic reactions, but they do not secrete digestive enzymes like pepsinogen.
Option C: Beta cells are endocrine cells located in the islets of Langerhans within the pancreas, not the stomach. Their primary function is to secrete insulin to regulate blood glucose levels.
Option D: Parietal cells are also located in the gastric glands but have a different function. They secrete hydrochloric acid (HCl) and intrinsic factor. While HCl is essential for converting pepsinogen to pepsin, the parietal cells do not secrete pepsinogen itself.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cellular secretions of the gastric glands as background academic context rather than a clinical decision trigger.
Understanding the distinct roles of gastric cells is fundamental for nurses to grasp the pathophysiology of conditions like peptic ulcer disease, gastritis, and pernicious anemia.
For example, damage to parietal cells in chronic gastritis can lead to both achlorhydria (lack of acid) and pernicious anemia (due to lack of intrinsic factor for B₁₂ absorption), impacting both digestion and hematopoiesis.
What if? If a patient is taking a proton pump inhibitor (PPI) like omeprazole, this drug specifically blocks the H+/K+-ATPase pump on parietal cells. This reduces acid secretion, which raises the stomach's pH. While this helps heal ulcers, it also reduces the activation of pepsinogen to pepsin, thereby decreasing the efficiency of protein digestion.

How to Approach the Question

First, identify the key term in the question, which is 'Pepsinogen'.
This is a factual recall question based on gastrointestinal physiology.
Recall the different types of cells found in the gastric glands of the stomach and their specific secretions.
Systematically evaluate each option:
Does this cell secrete pepsinogen?
If not, what does this cell secrete, and where is it located?

Concept Tested & Keywords

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E6 Histology Inderbir 11e p. 38-40

E6 Physiology Ganong 27e Vol 2 Part 1 p. 5-7

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

Practise the full AIIMS Rishikesh & Jodhpur NO - 2017

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