Which secretions help destroy pathogens in the stomach?

• A. Saliva
• B. Gastric secretions
• C. Bile
• D. Mucus

Answer: (B)

Gastric secretions create a highly acidic environment in the stomach that acts as a chemical barrier against ingested pathogens. The strong acid, hydrochloric acid, lowers the pH to around 1–3, which denatures microbial proteins and disrupts membranes, helping to kill or inactivate many bacteria and viruses. Pepsin, activated in this acidic setting, helps digest proteins and can contribute to antimicrobial effects indirectly. The mucus secreted by the stomach lining mainly protects the stomach tissue from damage by acid and enzymes rather than actively destroying microbes. Saliva contains antimicrobial components like lysozyme, but it acts primarily in the mouth, not in the stomach. Bile functions in the small intestine and has antimicrobial properties there, not in the stomach. Therefore, gastric secretions are the most effective in destroying pathogens in the stomach.