Which structure governs the passage of food material into the small intestine?

The pylorus, specifically the pyloric valve, plays a crucial role in regulating the flow of partially digested food, known as chyme, from the stomach into the small intestine. This valve is located at the lower end of the stomach and serves as a barrier that opens to allow chyme to enter the duodenum when it reaches a certain consistency and acidity level.

The opening and closing of the pyloric valve are tightly controlled, ensuring that food material is released gradually, which is vital for effective digestion and absorption in the small intestine. This regulation helps prevent overwhelming the intestine with too much chyme at once, allowing for optimal enzymatic action and nutrient absorption.

In contrast, the other structures listed do not govern the passage of food into the small intestine. The esophageal sphincter, for example, is responsible for controlling food entry into the stomach from the esophagus, while the cardiac sphincter functions as a barrier between the esophagus and stomach to prevent reflux. The duodenum, although part of the small intestine and crucial in the digestive process, is not the structure responsible for regulating the passage of material from the stomach into it.