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:
Large intestine
The taenia coli run the length of the large intestine. Because the taenia coli are shorter than the large bowel itself, the colon becomes "sacculated", forming the haustra of the colon which are the shelf-like intraluminal projections.