Which part of the small intestine is primarily responsible for chemical digestion?

The duodenum is primarily responsible for chemical digestion due to its unique role and the specific digestive processes that occur there. As the first section of the small intestine, it is directly connected to the stomach and receives chyme, which is a mixture of partially digested food and digestive juices.

In the duodenum, the acidic chyme is neutralized by bicarbonate secreted from the pancreas, creating an optimal pH for the enzymes to function. This section is also where bile from the liver emulsifies fats, allowing for more effective digestion and absorption. Additionally, the duodenum is where various enzymes from the pancreas—such as lipases, proteases, and amylases—operate to further break down carbohydrates, proteins, and fats.

While the jejunum and ileum are important for nutrient absorption, particularly the jejunum for the absorption of sugars and amino acids and the ileum for vitamin B12 and bile acids, the initiation of chemical digestion primarily occurs in the duodenum. The cecum, on the other hand, is more associated with the large intestine and the fermentation of undigested materials.