Which cells secrete an alkaline mucus to protect the lining of the small intestine from stomach acid?

• A. Parietal cells
• B. Chief cells
• C. Goblet cells
• D. Salivary amylase

Answer: (C)

Goblet cells secrete mucus that protects the lining of the small intestine. This mucus coats the inner surface, forming a barrier that cushions the epithelium and reduces damage from the acidic chyme that comes from the stomach. The mucus is part of an alkaline environment in the duodenum, helping neutralize some of the acid as chyme moves through the small intestine. Parietal cells and chief cells are stomach cells—parietal cells secrete acid (HCl) and chief cells secrete digestive enzymes—so they don’t provide the protective mucus in the small intestine. Salivary amylase is an enzyme from saliva, not a mucus-secreting product.