Final answer:
The duodenum's arrival of chyme initiates an enterogastric reflex that inhibits gastric secretion and controls gastric emptying. This mechanism ensures proper digestion by coordinating with liver, pancreas, and gallbladder activities, helped by the stomach's protective mucosal barrier.
Step-by-step explanation:
The arrival of chyme in the duodenum stimulates a neural reflex that inhibits gastric activity, which is a component of the intestinal phase of gastric secretion. This phase has both excitatory and inhibitory elements. Initially, the chyme prompts the release of the hormone intestinal (enteric) gastrin, which stimulates gastric juice secretion. However, the distension of the intestine from the chyme leads to an enterogastric reflex that inhibits this secretion and closes the pyloric sphincter, preventing further chyme from entering the duodenum.
The mucosal barrier of the stomach, consisting of a thick coating of bicarbonate-rich mucus, tight junctions among epithelial cells, and rapid cell turnover, protects against self-digestion by gastric enzymes. Gastric emptying is regulated by this barrier and the duodenum, to ensure the small intestine can efficiently process chyme.
The entry of chyme into the small intestine also initiates other hormonal and neural responses that coordinate the activities of the intestinal tract, pancreas, liver, and gallbladder, optimizing the digestive process.