Hepatic and gastrointestinal disorders

Abstract The liver and gastrointestinal (GI) tract are central to homeostasis, with highly interdependent functions. The concerted action of the liver and GI tract is required for complete digestion and absorption of dietary nutrients. These actions include the production and secretion of bile from the liver, enzymes and bicarbonate from the pancreas, and the enzymes and transport systems of the intestinal tract. Control is exerted by a complex hormonal system, including a range of hormones produced by the gut and pancreas, and by neuronal mechanisms. The nutrients thus absorbed from the gut are first directed to the liver via the portal vein. The liver is a large, complex organ with a diverse array of functions ranging from energy metabolism to detoxification of drugs. Hepatocytes are the main site of metabolic processes and comprise approximately 80% of total liver cells. Other cells include hepatic macrophages (Kupffer cells), lymphocytes, endothelial lining cells, biliary epithelial cells, and stellate cells. The liver receives a dual blood supply consisting of oxygen-poor and nutrient-rich blood via the portal vein from the gut and oxygen-rich blood via the hepatic artery. The arterial and venous blood mixes within the sinusoids and flows over the hepatocytes before draining away via the hepatic venous system.