The small intestines

The small intestines is the longest part of the digestive tract. It is 6 meters long but also the narrowest at 4 centimeters wide. It is looped, folded, and coiled into the lower part of the of the main body, the abdomen, and consist of 3 parts. First is the duodenum, about 25 centimeters long, which joins at the upper end to the stomach. It leads to the middle section, the jejunum which is 200 centimeters long. Third is the ileum which is 350 centimeters long. The ileum leads into the large intestine, in the lower right of the abdomen.

Similar as the lining of the stomach, the small intestine lining makes powerful enzyme-containing juices to break food into ever-smaller pieces. It also receives digestive juices from the pancreas and the liver, which also help the breakdown.

The small intestines is made up of many layers. The outer layer is called the serosa. The next 2 layers are muscles. The inner-most layer are villi.

The small intestine's inner-most lining is rippled into folds called plicae. These have thousand of tiny finger-like projections called villi. Each villus is about one millimeter long, and each has thousands os even tinier finger-like microvilli. The plicae, villi and microvilli give the small intestines a huge surface, bigger than the area of 5 single beds, to take in or absorb the greatest amount of digested nutrients from food.