What substance is secreted alongside amino acids, fatty acids, and high osmolarity in the duodenum?

The secretion of cholecystokinin (CCK) is closely associated with the presence of amino acids and fatty acids in the duodenum. When these macronutrients enter the duodenum, CCK is released from the intestinal mucosa in response to their presence. This hormone plays a crucial role in stimulating gallbladder contraction, which releases bile to aid in the digestion and emulsification of fats. Additionally, CCK promotes pancreatic enzyme secretion, further facilitating the digestion of proteins and fats.

High osmolarity in the duodenum can also trigger the secretion of CCK as part of the complex regulatory mechanisms involved in digestion. The presence of nutrients and elevated osmolarity signals the intestines to enhance digestive enzyme output and bile secretion. This coordinated response ensures that the body can effectively break down food components for absorption.

In contrast, other hormones listed, such as gastrin and secretin, have different primary functions. Gastrin primarily stimulates gastric acid secretion and the growth of gastric mucosa, while secretin is mainly focused on regulating the pH of the duodenum and stimulating bicarbonate secretion from the pancreas rather than promoting fat digestion directly. Insulin, on the other hand, is involved in glucose metabolism and energy