Question

Proenzyme pepsinogen is secreted from 'P' of gastric mucosa and converted into active enzyme pepsin on exposure to 'Q' secreted from 'R'. Choose the CORRECT combination of P, Q, and R.

• A. P - chief cells, Q - hydrochloric acid, R - oxyntic cells
• B. P - parietal cells, Q - enterokinase, R - chief cells
• C. P - oxynitic cells, Q - hydrochloric acid, R - parietal cells
• D. P - peptic cells, Q - gastrin, R - oxyntic cells

Hint:

Pepsinogen is converted into active pepsin when exposed to hydrochloric acid produced by oxyntic cells.

Answer 1

The Correct Option is A

Step 1: Understanding the secretion of pepsinogen.
Pepsinogen is secreted as an inactive proenzyme from the chief cells in the gastric mucosa. It is converted into active pepsin upon exposure to hydrochloric acid (HCl) secreted by the oxyntic cells.

Step 2: Analyzing the options.
(A) P - chief cells, Q - hydrochloric acid, R - oxyntic cells: Correct — Pepsinogen is secreted by the chief cells and is activated by hydrochloric acid produced by the oxyntic cells.
(B) P - parietal cells, Q - enterokinase, R - chief cells: Incorrect — Parietal cells secrete HCl, not pepsinogen, and enterokinase is not involved in this process.
(C) P - oxynitic cells, Q - hydrochloric acid, R - parietal cells: Incorrect — Oxyntic cells produce HCl, not pepsinogen.
(D) P - peptic cells, Q - gastrin, R - oxyntic cells: Incorrect — Peptic cells do not secrete pepsinogen directly, and gastrin is not directly involved in the activation of pepsinogen.

Step 3: Conclusion.
The correct answer is (A) P - chief cells, Q - hydrochloric acid, R - oxyntic cells, as it describes the correct mechanism of pepsinogen activation.