What is the most likely effect on peptide secretion when fatty acids are infused into the proximal small intestine of an animal?

• A. Increased amylase
• B. Increased cholecystokinin
• C. Increased pancreatic polypeptide
• D. Increased secretin

Answer: (B)

Infusing fatty acids into the proximal small intestine stimulates the secretion of cholecystokinin (CCK). When fatty acids enter the small intestine, they are detected by specialized enteroendocrine cells in the intestinal mucosa that respond by releasing CCK into the bloodstream. CCK plays a crucial role in the digestive process; among other functions, it promotes the secretion of pancreatic enzymes (including lipases) that are involved in fat digestion and encourages the gallbladder to release bile, which helps emulsify fats.

The presence of dietary fats is a significant physiological trigger for CCK release because it signals the body that digestion of fat is required. This hormone then potentiates the digestive processes by not only increasing enzyme secretion but also helping regulate appetite and stimulate gut motility.

In summary, the infusion of fatty acids leads to an increase in cholecystokinin secretion, which is key for facilitating the digestive process of fats in the proximal small intestine.