The liver is your largest internal organ. It is an incredible biological factory with hundreds of functions. The liver is part of the digestive, the endocrine and the immune systems. One job is making the digestive fluid called bile. Another is processing and storing vitamins, minerals and other substances. Blood flows from the heart and intestines into the liver where it oozes through some 50,000 tiny hepatic lobules. These break down nutrients and filter old cells from blood.