Which of the following are parts of the small intestine?

The small intestine consists of three primary sections: the duodenum, jejunum, and ileum. Each of these sections plays a crucial role in the digestive process.

The duodenum is the first section of the small intestine, where a significant amount of digestion takes place, aided by enzymes from the pancreas and bile from the liver. Following the duodenum, the jejunum is primarily responsible for the absorption of nutrients, as its walls are lined with villi and microvilli that increase the surface area for absorption. Lastly, the ileum is the final part of the small intestine, which continues the absorption process and also plays a role in the absorption of specific nutrients that were not absorbed in the jejunum, as well as bile salts and vitamin B12.

This distinction is important because options that include parts of other digestive organs, like the stomach or colon, do not accurately represent the structure of the small intestine. By identifying the correct components—duodenum, jejunum, and ileum—one can better understand the anatomy and functions of the small intestine in the context of veterinary medicine.