Multiple choice

The epithelial cells lining the stomach of vertebrates is protected from damage by HCl because

  1. HCl acid is too dilute

  2. The epithelial cells are resistant to the action of HCl acid

  3. HCl is neutralised by alkaline gastric juice

  4. The epithelial cells are covered with a mucous secretion

  5. none of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Gastric epithelial cells are protected by a thick layer of mucus secreted by goblet cells and surface epithelial cells. This mucus forms a physical barrier and contains bicarbonate that neutralizes acid at the cell surface. The HCl is NOT too dilute (it's very potent), epithelial cells are NOT inherently acid-resistant, and HCl is NOT neutralized by alkaline gastric juice (the stomach is acidic).

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