text: Each villus has a network of capillaries and fine lymphatic vessels called lacteals close to its surface. The epithelial cells of the villi transport nutrients from the lumen of the intestine into these capillaries (amino acids and carbohydrates) and lacteals (lipids). The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by our body. The material that remains undigested and unabsorbed passes into the large intestine.
  Absorption of the majority of nutrients takes place in the jejunum, with the following notable exceptions:
  Iron is absorbed in the duodenum.
  Folate (Vitamin B9) is absorbed in the duodenum and jejunum.
  Vitamin B12 and bile salts are absorbed in the terminal ileum. Vitamin B12 will only be absorbed by the ileum after binding to a protein known as intrinsic factor.
  Water is absorbed by osmosis and lipids by passive diffusion throughout the small intestine.
  Sodium bicarbonate is absorbed by active transport and glucose and amino acid co-transport
  Fructose is absorbed by facilitated diffusion.
  Immunological
  The small intestine supports the body's immune system.  The presence of gut flora appears to contribute positively to the host's immune system.