The statement "as long as there is chyme in the duodenum, it will continue to stimulate gastric secretion" is not accurate. In reality, the presence of chyme in the duodenum triggers a complex regulatory response that mostly inhibits gastric secretion.
How chyme in the duodenum affects gastric secretion
- When chyme enters the duodenum, intestinal receptors and hormones are activated.
- Initially, there is a brief stimulation of gastric secretion by intestinal gastrin released from duodenal mucosal cells.
- However, as the duodenum fills with chyme, inhibitory signals such as the enterogastric reflex and hormones like secretin and cholecystokinin are released, which suppress further gastric secretion and slow gastric emptying to prevent overloading the duodenum.
- Secretin is released in response to acidic chyme entering the duodenum and it inhibits gastric acid secretion while stimulating pancreatic bicarbonate secretion to neutralize chyme acidity.
- Cholecystokinin (CCK) released in response to fatty acids and amino acids also inhibits gastric emptying and secretion.
Summary
Rather than stimulating gastric secretion continuously, chyme presence in the duodenum initiates a negative feedback mechanism that decreases gastric secretions once the duodenum begins processing the chyme. This regulatory process protects the intestine and modulates digestion efficiency.
Therefore, the correct physiological understanding is that chyme in the duodenum primarily inhibits gastric secretion rather than continuously stimulating it.