Internal organs. Computer artwork of a human body showing the internal organs. Within the chest are the lungs, the site of gaseous exchange; oxygen enters the blood and carbon dioxide leaves. To the lower left of the lungs is the liver, which has various functions including detoxification of the blood and bile production. To the right of the liver is the stomach, where digestion of food begins. The stomach empties into the intestines. The large intestines are seen surrounding the small intestines at centre. The intestines finish the digestion of food and absorb nutrients and water from it. At centre bottom are the penis and testes, the male reproductive organs.