Wikijunior:Human Body/Digestive System/Small Intestine

The small intestine is a part of the digestive system. It is the most important organ for the digestion of food.



What does the small intestine look like?
The small intestine is a long, narrow tube that is all coiled up in the lower part of our abdomen (the part of our body we usually call our "stomach"). It is over 20 feet (6 meters) long! This is the largest part of the digestive system. The only way the small intestine can fit into our bodies is by curling and looping to fit in a small space.

What are the parts of the small intestine?
The small intestine is about 20 feet long

The first part of the small intestine is called the duodenum. The middle part is the jejunum. This is where most of the nutrients in food are absorbed into the blood. The last part of the small intestine is called the ileum. This part connects to the large intestine.

The lining of the small intestine is covered with tiny finger-like projections called villi. They look almost like carpet. The villi help the nutrients in food to be absorbed into the blood.



What is the function of the small intestine?
The small intestine is where most digestion takes place. Food is broken down into smaller and smaller particles. Finally, when the particles are small enough, they are absorbed into the blood, and the blood carries the nutrients to all parts of the body.

How does the small intestine interact with other parts of the body?
The small intestine is connected to the stomach. Food that the stomach has begun to digest moves into the small intestine. After it moves through the small intestine, food moves on the large intestine. Like other organs, the small intestine gets oxygen from blood vessels. The blood in the small intestine also carries the nutrients from food to the rest of the body. The circulatory system allows this to happen.

The small intestine gets enzymes from two important glands, called the liver and the pancreas. The liver is the largest organ in our bodies. It makes a liquid called bile that helps digest fat. The bile is stored in another organ called the gall bladder. The pancreas makes a juice that breaks down sugars and starches.