Pancreatic proteases (e.g., trypsin) are secreted as inactive zymogens. Why is zymogen secretion important, and what activates them in the small intestine?

Zymogen secretion prevents autodigestion of the pancreas; enterokinase (enteropeptidase) on the duodenal brush border activates trypsinogen to trypsin, which then activates other proteases.

Secreting active proteases would improve digestion efficiency, so zymogen secretion is an evolutionary error corrected by intrapancreatic inhibitors rather than activation in the intestine.

Zymogens are secreted to speed up hormone release from the pancreas, with insulin serving as the primary molecular activator for all zymogens once food reaches the ileum.

Zymogen secretion increases protease activity inside the pancreas to help digest endogenous proteins during fasting; pepsin from the stomach is the activator of pancreatic zymogens in the duodenum.