In previous communications1 it has been pointed out that the external pancreatic secretory response to a meal can be divided into two phases with reference to the sites at which the stimuli are acting: (1) the cephalic phase, and (2) the intestinal phase. A comparison of the amount of secretion produced during these two phases has shown that the intestinal phase is unquestionably the most important. A gastric phase was shown not to exist, since it was found that foods, and other possible excitants, when placed in the stomach failed to excite the pancreas to secrete.
The most important questions that confront any one interested in external pancreatic secretion are: 1. What substances acting in the intestine excite the pancreas to secrete? 2. What is the mechanism, or mechanisms, concerned in this excitation? 3. Do these mechanisms operate in normal digestion? 4. What is the effect of various disease
IVY AC. PHYSIOLOGY OF EXTERNAL PANCREATIC SECRETIONVI. FURTHER STUDIES. JAMA. 1927;89(13):1030–1034. doi:10.1001/jama.1927.02690130018008