What is the first major section of the small intestine where digestive enzymes enter?

The correct answer is the first major section of the small intestine where digestive enzymes enter is the duodenum. This segment is crucial in the digestive process because it is here that most of the chemical digestion occurs. The duodenum receives chyme from the stomach along with bile from the gallbladder and pancreatic juices from the pancreas. These substances provide essential enzymes that break down carbohydrates, proteins, and fats, allowing for their absorption as the chyme continues through the small intestine.

In contrast, the jejunum and ileum, which follow the duodenum, primarily focus on the absorption of nutrients rather than the introduction of digestive enzymes. The colon, on the other hand, is part of the large intestine and is involved in the absorption of water and the formation of feces, not in the initial enzymatic digestion of food. Hence, the duodenum serves as the critical entry point for digestive enzymes, making it the first major section of the small intestine involved in this process.