Which structure in the small intestine contains fewer, smaller villi?

The ileum is characterized by having fewer and smaller villi compared to the other sections of the small intestine. This is primarily because the ileum's main role is the absorption of nutrients rather than maximizing surface area for absorption, which is a primary function of the duodenum and jejunum.

In the duodenum, the presence of larger and more numerous villi is beneficial because this section is where most of the digestion occurs. It receives digestive juices from the pancreas and bile, which aids in breaking down food more efficiently.

The jejunum, being the middle part of the small intestine, is also adapted for a high degree of nutrient absorption, featuring plenty of long and closely packed villi to facilitate this process.

In contrast, the ileum is devoted more to the absorption of specific nutrients such as vitamin B12 and bile salts. Hence, its villi are diminished in size and number in comparison to the earlier sections of the small intestine, allowing for efficient absorption while accommodating the necessary functions of this part of the digestive system.

Understanding the differences in structure and function among the sections of the small intestine is crucial for grasping how nutrient absorption is optimized within the digestive tract.