Liver

Blood from the intestines, rich in nutrients from digested food, flows to the liver. The liver is in the upper right of the abdomen, with most of it's bulk behind the lower right ribs. The reddish-brown, smooth-surfaced, wedge-shape liver has more than two hundred different task, mainly to do with metabolism (body chemistry). It breaks down some nutrients, builds up others, stores some until needed, and releases others when their levels in the blood fall to low.

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.

The large intestine, appendix and rectum

After the food leaves the small intestine or small bowel, comes the large intestine or large bowel, also called the colon. It is wide, about 6 to 7 centimeters across, but shorter than the small intestine, at about 150 centimeters. It passes up the right side of the abdomen, across below the liver and stomach, down the left side, and then curves in an S shape to the lower abdomen.

The large intestine contains microbes known as gut bacteria. These gut bacteria break down certain kinds of food, especially plant foods, so the body can absorb the nutrients. The large intestine also absorbs much of the water from the leftover digested food, turning it into squishy brown lumps called faeces or bowel motions.

The appendix is a small part of the digestive tract, about the size of a little finger. It is the junction of the small and large intestines, in the lower right of the abdomen. The appendix is hollow inside and links to the main digestive tract, but does not lead anywhere else. It does not seem to have an important role.

At the end of the large intestine, the leftover and undigested contents called faeces pass into the last part of the main tract. This is the rectum which is about 15 centimeters long. The faeces stay here until it is convenient to remove them from the body. This is done by squeezing the muscles of the abdomen, to push the faeces through the loosened ring of muscle at the end of the tract, called the anus.