Many scientists such as, Pawlow, Popielski, Wertheimer, Lepage, Bayliss, Starling, Claude Bernard, and Bernard Pavlov have contributed their knowledge to the better understanding of the mechanisms of the pancreatic secretion. They made many observations and held many experiments to come to the conclusions that they have. .
For starters Claude Bernard was the first to propose that substances present in the intestine produced a stimulating effect on external pancreatic secretion. But the main and most important discoveries were made by Bayliss and Starling in 1902.
The main question though that all of these scientists wanted to know was: Why is Pancreatic Secretion evoked by the introduction of acid into the duodenum? .
Starting from way back in History Bernard Pavlov discovered that pancreatic secretion could be evoked by the introduction of ether into the stomach or into the duodenum. The duodenum is the beginning portion of the small intestine, starting at the lower end of the stomach and extending to the jejunum. Extending from Pavlov's studies a man by the name of Pawlow went further into researching pancreatic secretion and now has most of the credit for knowledge of secretion. Pawlow showed that the flow of pancreatic juices begins with the entry of chyme; which is the thick semi fluid mass of partly digested food that is passed from the stomach to the duodenum. The chyme is entered into the duodenum and not excited directly by the presence of food in the stomach. Chyme is mostly effective because of its acidity. Secretion also occurs when hydrochloric acid is introduced. The effects not only occur when substances such as chyme and hydrochloric acid are introduced but water and oil also. Pawlow regards that the secretion evoked by the presence of acid in the duodenum as a reflex in the origin. This happens because the substances as earlier stated excite different nerve endings, producing different nerve impulses.