1. Cephalic Phase
  • Describes the activity that occurs in anticipation of a meal
  • Signals are transmitted from the brain via the vagus nerve causing release of acetylcholine in nerve endings in the pancreas
  • Causes moderate amounts of enzymes to be secreted into the pancreatic acini, accounting for about 20 percent of the total secretion after a meal
  • Only small amounts of water is secreted which limits flow of enzymes through ducts at this stage
2. Gastric Phase
  • Continues neural stimulation of enzyme secretion continues, accounting for another 5 to 10 percent of pancreatic enzymes secreted after a meal
  • Fluid secretion again remains small, limiting amount that reaches the duodenum
3. Intestinal Phase
  • As chyme enters the small intestines the pancreatic secretions become copious
  • Mainly in response to the hormone secretin