Illustration of the liver (grey) and gallbladder (green), seen from the rear. The gallbladder stores and concentrates bile produced by the liver and secretes it into the small intestines where it helps the body to digest fat. At bottom is the inferior vena cava (purple), the bodys largest vein. It carries deoxygenated blood from the lower body back to the heart. Above it is the portal vein (purple, centre), which drains deoxygenated blood from the liver. From Traite dAnatomie Humaine, Vol. 4 (1905) by French anatomist Leo Testut (1849-1925).