The small intestine mixes chyme with which secretions?

• A. Gastric acid and pepsin
• B. Saliva and mucus
• C. Intestinal juices, pancreatic juices and bile salts
• D. Respiratory enzymes

Answer: (C)

Chyme entering the small intestine is mixed with digestive secretions from multiple sources to continue breaking down nutrients. Intestinal juices from the mucosa add enzymes and protective mucus, pancreatic juice delivers bicarbonate to neutralize acid plus enzymes (amylase, lipase, proteases) to digest carbohydrates, fats, and proteins, and bile salts from the liver emulsify fats to aid their digestion. This combination makes the small intestine the main site where digestion proceeds after the stomach empties.

Gastric acid and pepsin come from the stomach, not the small intestine. Saliva and mucus are from the mouth and upper digestive tract, not the primary small-intestinal mix. Respiratory enzymes are unrelated to digestion in the gut.