Final answer:
The central mechanism for secretion from both duct and secretory cells is regulated by hormones like secretin and CCK. Secretin stimulates duct cells to release bicarbonate-rich pancreatic juice, while CCK stimulates acini to secrete enzyme-rich pancreatic juice. Parasympathetic regulation occurs during the cephalic and gastric phases of gastric secretion.
Step-by-step explanation:
The central mechanism for secretion from both duct and secretory cells is regulated by hormones and the parasympathetic nervous system. When acidic chyme enters the duodenum, it stimulates the release of secretin, which causes duct cells to release bicarbonate-rich pancreatic juice. The presence of proteins and fats in the duodenum stimulates the secretion of CCK, which stimulates the acini to secrete enzyme-rich pancreatic juice and enhances the activity of secretin. Parasympathetic regulation occurs mainly during the cephalic and gastric phases of gastric secretion, when vagal stimulation prompts the secretion of pancreatic juice.