Final answer:
The presence of bile and pancreatic juice in the duodenum can slow down the entry of chyme from the stomach into the small intestine.
Step-by-step explanation:
When chyme enters the small intestine from the stomach, its entry can be slowed by the presence of certain substances in the duodenum. One such substance is bile, which is produced in the liver and stored in the gallbladder before being released into the duodenum. Bile helps in the digestion and absorption of fats. Another substance that can slow down the entry of chyme is pancreatic juice, which contains enzymes that break down proteins, carbohydrates, and fats. These substances need time to mix and react with chyme, which slows down its movement through the small intestine.