Final answer:
At the hepatopancreatic ampulla, bile and pancreatic enzymes mix together before entering the duodenum.
Step-by-step explanation:
The substances from different organs that would mix together at the hepatopancreatic ampulla are bile and pancreatic enzymes. This occurs when the larger duct of the pancreas fuses with the common bile duct, carrying bile from the liver and gallbladder, just before entering the duodenum. The presence of proteins and fats in the duodenum stimulates the secretion of CCK, which then stimulates the acinar cells to secrete enzyme-rich pancreatic juice and enhances the activity of secretin, further promoting the release of bile and digestive enzymes into the small intestine.