1. Cephalic stage: This stage begins before the food enters the stomach. At this stage, 20 percent of gastric juice is secreted.
2. Gastric phase: The gastric phase is the time when food settles in the stomach. At this stage, 70 percent of gastric juice is secreted for digestion.
3. Intestinal Phase: When food enters the small intestine from the stomach, the intestinal phase begins. At this stage very little amount of gastric juice is secreted.