What substance is stimulated by CCK to help emulsify fats in the small intestine?

Bile is the substance stimulated by Cholecystokinin (CCK) to help emulsify fats in the small intestine. When fats enter the small intestine, CCK is released from the intestinal lining and triggers the gallbladder to contract, releasing bile into the small intestine. Bile contains bile salts that play a vital role in emulsifying fats, breaking them down into smaller droplets to increase the surface area for digestion by enzymes. This emulsification is crucial because it allows lipase, the enzyme responsible for fat digestion, to effectively act on the fats.

The other substances mentioned do not have the primary function of emulsifying fats. Pancreatic enzymes are involved in the digestion of proteins and carbohydrates, bicarbonate primarily neutralizes stomach acid to provide an optimal pH for digestive enzymes, and acid (hydrochloric acid) is important in the stomach for digestion but does not contribute to fat emulsification in the small intestine.