Gastrointestinal tract
The small intestine begins at the duodenum and is a tubular structure, usually between 6 and 7 m long. Its mucosal area in an adult human is about 30 m. Its main function is to absorb the products of digestion (including carbohydrates, proteins, lipids, and vitamins) into the bloodstream. There are three major divisions:
Short bowel syndrome
The length of the small intestine can vary greatly, from as short as to as long as . On average it is about . Due to this variation it is recommended that following surgery the amount of bowel remaining be specified rather than the amount removed.