In biology the small intestine is the part of the gastrointestinal tract between the stomach and the large intestine and comprises the duodenum, jejunum, and ileum. It is where the vast majority of digestion takes place. Nutrients diffuse through the villi, projections sticking out of the walls of the small intestine, into the blood. In humans over 5 years old it is approximately 7 m long and can vary from...
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