The small intestine is where food breakdown continues and absorption of nutrition occurs. The small intestine is about 7 meters long and is divided into three sections: duodenum, jejunum and ileum. Different types of nutrition are absorbed in the different sections of the small bowel.
As food passes from the stomach, it is bathed in secretions of the liver (bile) and pancreas, breaking down fats and proteins and carbohydrates. There are small, finger-like projections from the surface of the small bowel, call villi. If you look under a microscope you can see where much of the nutrition breakdown and absorption occurs.
Eventually, most of the nutrients are extracted from the food and the waste is passed into the colon.