Unit Thirteen: Metabolism and Temperature Regulation Chapter 70: The Liver as an Organ Guyton and Hall, Textbook of Medical Physiology, 12th edition

Basic Properties Physiologic Anatomy of the Liver Largest organ of the body, contributes about 2% of the total body weight Functional unit is the liver lobule; liver contains 50,000-100,000 individual lobules

Physiologic Anatomy of the Liver Basic Properties Physiologic Anatomy of the Liver Fig. 70.1 Basic structure of a liver lobule

Basic Properties Hepatic Vascular and Lymph Systems Blood flows through the liver from the portal vein and hepatic artery Liver has high blood flow and little vascular resistance Liver functions as a blood reservoir Liver has high lymph flow

Basic Properties Regulation of Liver Mass-Regeneration The liver can restore itself after significant hepatic tissue loss Control mechanisms are largely unknown but may be regulated by hepatocyte growth factor (HGF) Once the liver has returned to its normal size, growth is inhibited, possibly by cytokines (i.e. transformng growth factor-beta)

Basic Properties Hepatic Macrophage System Serves a Blood Cleansing Function Kupffer cells- large phagocytic macrophages that line the hepatic venous sinuses Removes approximately 99% of the bacteria entering the portal blood from the intestinal tract

Basic Properties Metabolic Functions of the Liver Carbohydrate metabolism 1) storage of large amounts of glycogen 2) conversion of galactose and fructose to glucose 3) gluconeogenesis 4) formation of many chemical compounds from intermediate products of cbh metabolism 5) important for maintaining a normal blood glucose concentration

Basic Properties Metabolic Functions of the Liver Fat metabolism 1) oxidation of fatty acids to supply energy for other body functions 2) synthesis of large quantities of cholesterol, phopholipids, and most lipoproteins 3) synthesis of fat from proteins and cbhs

Basic Properties Metabolic Functions of the Liver c. Protein metabolism 1) deamination of amino acids 2) formation of urea for removal of ammonia from the body fluids 3) formation of plasma proteins 4) Interconversions of the various amino acids and synthesis of other compounds from amino acids

Basic Properties Metabolic Functions of the Liver d. Other metabolic functions 1) storage site for vitamins 2) stores iron as ferritin 3) forms the blood substances used in coagulation 4) removes or excretes drugs, hormones, and other substances