Final answer:
Pancreatic secretions are converted by the duodenum through the actions of secretin and CCK, which lead to the release of bicarbonate and digestive enzymes necessary for neutralizing acidic chyme and digesting nutrients like proteins.
Step-by-step explanation:
The conversion of pancreatic secretions by the duodenum is an intricate process involving several components and various enzymes. When the acidic chyme from the stomach enters the duodenum, it triggers the release of two key hormones: secretin and cholecystokinin (CCK). Secretin prompts the pancreas to produce an alkaline bicarbonate solution, which helps neutralize the acidity of the chyme. Concurrently, CCK stimulates the pancreas to release pancreatic juices rich in digestive enzymes, and it also induces the gallbladder to discharge bile into the duodenum to aid in digestion, particularly in the emulsification of lipids.
The pancreatic juices contain enzymes such as trypsin and chymotrypsin which are key for the digestion of proteins in the duodenum. These enzymes break down proteins into peptides, which are further digested by peptidases into amino acids, allowing for absorption. The bicarbonate and mucus secreted by the pancreas and Brunner's glands also protect the intestinal lining from the acidic chyme, while enabling the optimal functioning of digestive enzymes.