What substance inhibits gastric emptying by releasing CCK?

The correct choice is fat, which plays a significant role in the regulation of gastric emptying through the release of cholecystokinin (CCK). When fats enter the small intestine, they stimulate the release of CCK from I-cells located in the intestinal mucosa. CCK serves several functions, including stimulating gallbladder contraction to release bile and promoting digestive enzyme secretion from the pancreas.

Most importantly, CCK inhibits gastric emptying. This delay allows for better digestion and absorption of nutrients, particularly fats, which require more time for emulsification and absorption processes. The presence of fats in the duodenum signals the body to slow down the rate at which the stomach empties its contents, ensuring that the digestive system effectively processes the incoming food.

While proteins and carbohydrates can also influence gastric emptying and stimulate CCK release, fats are more potent in this role. Water does not significantly affect the secretion of CCK or the rate of gastric emptying, as it is absorbed quickly and does not require extensive digestion. Thus, fat is the primary substance associated with the inhibition of gastric emptying through the action of CCK.