Why does the mucus lining of the stomach not get digested by pepsin under normal conditions?
Generated by claude-sonnet-4-6 · 2026-06-15 06:44 · grounding rag
Model Answer
The gastric glands in the stomach wall secrete mucus along with pepsin and hydrochloric acid. This mucus forms a protective coating over the inner lining of the stomach. It acts as a barrier, preventing pepsin (and HCl) from coming into direct contact with the stomach wall, thus protecting it from digestion under normal conditions.
Source: Life Processes, Section 5.2.4 – Nutrition in Human Beings
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Explanation
- The key fact examiners want: mucus is secreted by gastric glands and it protects the inner lining from pepsin and acid.
- Mention both what mucus is (a secretion of gastric glands) and what it does (forms a protective layer/barrier).
- The passage directly states: "The mucus protects the inner lining of the stomach from the action of the acid under normal conditions." Extend this logically to pepsin as well — both are produced together, and mucus guards against both.
- Avoid writing lengthy explanations; two crisp points are sufficient for 2 marks.