Secretin is a peptide hormone involved in digestive regulation, pancreatic bicarbonate secretion, gastrointestinal pH balance, and coordination of communication between the stomach, pancreas, and small intestine. Secretin functions primarily as a protective endocrine signal responding to acidic gastric contents entering the duodenum.
The hormone stimulates pancreatic bicarbonate secretion, supports neutralization of intestinal acidity, promotes optimal digestive enzyme activity, and contributes to regulation of gastric emptying and bile secretion. Secretin also participates in communication pathways coordinating pancreatic physiology, intestinal protection, and nutrient-processing adaptation. Through these actions, the hormone helps maintain balanced digestive conditions within the upper gastrointestinal tract.
Secretin is produced by S cells located mainly within the duodenum and upper small intestine. The hormone is synthesized and released in response to acidic chyme entering the intestinal lumen following gastric digestion.
Production increases rapidly when luminal pH decreases within the duodenum. Intestinal endocrine cells continuously monitor digestive conditions and regulate hormone release according to acid exposure and nutrient-processing demands.
Secretin secretion is regulated primarily by duodenal acidity and luminal hydrogen ion concentration. Acidic gastric contents strongly stimulate release, while restoration of intestinal pH suppresses secretion through local feedback mechanisms.
The hormone acts through secretin receptor systems linked to cyclic AMP signaling, pancreatic bicarbonate transport pathways, bile secretion mechanisms, and gastrointestinal motility regulation. Nutrient composition, digestive activity, and enteric nervous-system signaling may also influence secretion dynamics. Through these integrated gastrointestinal endocrine systems, secretin coordinates acid neutralization, pancreatic communication, digestive protection, and intestinal physiological balance.
Secretin regulates bicarbonate secretion and coordinates digestion between the stomach and small intestine.
