Final answer:
Increased acid from stomach chyme entering the duodenum stimulates secretin release, which in turn prompts pancreatic bicarbonate secretion to neutralize the acid.
Step-by-step explanation:
An increase in acid from the chyme leaving the stomach stimulates an increase in the secretion of secretin. When acidic chyme enters the duodenum, it prompts the release of secretin from the small intestine.
In response, secretin stimulates the pancreas to produce bicarbonate-rich pancreatic juice to neutralize the acidic environment, thus safeguarding the integrity of the duodenal lining and ensuring the proper functioning of digestive enzymes.