Final answer:
The intestinal phase of gastric regulation occurs in the small intestine, where chyme triggers hormonal and neural events, including the release of intestinal (enteric) gastrin, which briefly excites gastric juice secretion, followed by the intragastric reflex that inhibits secretion and closes the pyloric sphincter.
Step-by-step explanation:
The intestinal phase of gastric regulation is facilitated by events that occur in the small intestine, where chyme stimulates the release of hormones and receptors that initiate neural reflexes. During this phase, the presence of chyme in the small intestine triggers digestive secretions to control the rate of gastric emptying.
Additionally, when chyme enters the small intestine, it does not only prompt gastric emptying; it also triggers other hormonal and neural events that coordinate the activities of the intestinal tract, pancreas, liver, and gallbladder.
Hormones such as intestinal (enteric) gastrin are released by the intestinal mucosal cells when partially digested food fills the duodenum. This hormone briefly stimulates further gastric juice secretion. However, as the intestine becomes distended with chyme, the enterogastric reflex suppresses secretion and causes the pyloric sphincter to close, preventing more chyme from entering the duodenum. This reflex action effectively regulates the stomach and its emptying process.