Why Your Stomach Doesn't Digest Itself

The real science

Your stomach mixes food with acid and digestive enzymes, yet its lining usually survives this hostile environment. The secret is not acid-proof flesh. It is a layered defence. Cells at the stomach’s surface produce mucus, which forms a protective coating. Bicarbonate within that coating helps neutralise acid near the cells, keeping conditions there much gentler than in the stomach’s main cavity. Tight connections between neighbouring cells also help prevent acid from slipping through. A good blood supply supports the tissue, and repair processes replace damaged cells. These systems work together; mucus alone is not an invincible shield. If the protective barrier is disrupted, inflammation or ulcers can occur. The bacterium Helicobacter pylori and certain medicines are important causes of stomach ulcers. This cartoon is a simplified explanation of normal digestion, not a guide to diagnosing pain or treating disease. For ongoing symptoms, seek advice from a qualified healthcare professional rather than a cartoon stomach.

Don’t try anything shown in this video.

Follow the facts

• Scientific American — Why don’t our digestive acids corrode our stomach linings?
• BBC Science & Nature — Stomach

Our illustrations simplify anatomy and scale. Educational content only; not medical advice.