The duodenum is the first section of your small intestine, located right after your stomach. When food leaves your stomach after being churned and mixed with acid, it enters this curved, C-shaped tube about ten inches long.

The duodenum is where a lot of the important work of digestion happens. Your pancreas and liver send powerful digestive juices into the duodenum through small tubes. These juices break down proteins, fats, and carbohydrates so your body can absorb nutrients. Think of your stomach as a blender that mashes everything up, and the duodenum as the chemical processing plant that actually extracts what your body needs.

While you have about twenty feet of small intestine total, this first ten inches does some of the most important chemical work in your entire digestive system.

When doctors talk about ulcers in the duodenum, they mean painful sores that can develop there, often from too much stomach acid. The duodenum has special cells that produce a protective coating to shield itself from the acidic food coming from the stomach.