Which substance secreted by the stomach helps protect the stomach lining?

• A. Mucus
• B. Bile
• C. Pancreatic juice
• D. Saliva

Answer: (A)

Protections of the stomach lining come from a mucus layer secreted by the stomach’s mucous cells. This mucus coats the inner surface and, with bicarbonate included in the secretion, creates a buffered barrier that keeps the highly acidic gastric juice from damaging the tissue. In other words, mucus is the protective substance produced right in the stomach and essential for lining safety. Bile is made by the liver and helps with fat digestion in the small intestine, pancreatic juice comes from the pancreas into the small intestine to aid digestion, and saliva from the mouth helps lubricate and begin digestion there—none of these protect the stomach lining the way mucus does.