What controls the passage of chyme from the last region of the stomach to the duodenum region of the small intestine?

The chyme is pushed along the small intestine by muscle contractions called peristaltic waves. Most of the chemical digestion and breakdown of the food happens in the duodenum. Food is mixed with bile from the gallbladder and digestive juices from the pancreas.

Explanation:

Chyme, a thick semifluid mass of partially digested food and digestive secretions that is formed in the stomach and intestine during digestion. In the stomach, digestive juices are formed by the gastric glands; these secretions include the enzyme pepsin, which breaks down proteins, and hydrochloric acid.

The stomach has four major regions: the cardia, fundus, body, and pylorus. The addition of an inner oblique smooth muscle layer gives the muscularis the ability to vigorously churn and mix food.