Symposium on diagnosis of pancreatic disease Pancreatic function tests: The physiological background

It would seem self-evident that a good knowledge of the physiology of pancreatic secretion should be a preliminary quest of the physician in order that deviation from normal function can be recognized and understood and that pancreatic function tests may be formulated and based on sound principles. To this end a number of questions must be posed. What is the function of the pancreas? How is the gland controlled? What measurements must be made to assess function? What are the normal ranges of the parameter measured? Briefly the function of the pancreas is to provide the appropriate enzymes for the hydrolysis of food-stuffs so that absorption and further digestion can occur, and to provide electrolyte to carry the enzymes into the duodenum and there, with the secretions of the liver and Brunner's gland, provide the appropriate milieu for enzymatic action. The Control of Pancreatic Secretion The control of pancreatic secretion may be con-veniently classified for descriptive purposes into three phases, according to the site at which the stimuli act to excite secretion. 1 CEPHALIC PHASE Pancreatic secretion is initiated by unconditioned and conditioned reflexes which are evoked on eating a meal. The taste of food, its sight, the accompanying noises and smell all combine reflexly to excite efferent fibres lying in the vagus nerves (Preshaw