Liver Functions 27-Apr-19 Liver Functions

Functional Anatomy Liver is the largest solid viscera 1.5 kg Important for regulation of energy metabolism Stores Carbohydrate (Glycogen) Regulate composition of blood Secretes bile 27-Apr-19 Liver Functions

Structure Liver is made up of plates or sheets of cells Separated by sinusoids Lined by reticulo-endothelial cells Tunneled by portal tracts and hepatic central vein 27-Apr-19 Liver Functions

Structure The portal tracts consist of Branches of portal vein Hepatic artery Small bile duct Lymph duct Blood flows from these portal tract into central vein 27-Apr-19 Liver Functions

Structure Bile excreted by hepatic cells Into canaliculi Flows into bile duct 27-Apr-19 Liver Functions

Blood flow through the liver Zone 1 Zone 3 Zone 2 Press=5 mm Hg PO2 = 30 mm Hg 60 – 65% Sat with O2 Press =10 mmHg PO2 = 60mm Hg, 80 – 90% Sat with O2 27-Apr-19 Liver Functions

Blood Supply Portal blood flow is Liver O2 extraction Approx 1.5 liters/min (about 25% CO) 70% from portal vein 30% from hepatic artery Hepatic artery provides 50% of O2 supply Liver O2 extraction 55 ml/min 27-Apr-19 Liver Functions

Functions of Liver Synthetic Detoxification various substances Plasma proteins Clotting factors Fibrinogen, prothrombin, factors V, VII, IX, X, XIII Fibrinolytic factors Bile salts Detoxification various substances Hydroxylation, oxidation Responsible for metabolism of drugs 27-Apr-19 Liver Functions

Functions Conjugation Conversion into glucoronide or sulphate Bilirubin, Steroid hormones Detoxification of drugs and foreign substances Oxidation, reduction, demythylation Followed by conjugation Makes substances water soluble Excreted by kidneys 27-Apr-19 Liver Functions

Functions Storage function Metabolic functions Glycogen , vitamins A,D,E,K Vit. B12 (1- 3 yrs) Metabolic functions Liver as a regulator of energy metabolism Carbohydrates, fats and protein 27-Apr-19 Liver Functions

Metabolic Functions Carbohydrates Storage of glycogen Glucose Glycogen Coversion of Galactose to Glucose Gluconeogenesis Lactate Amino acids Glucose Glycerol 27-Apr-19 Liver Functions

Functions Maintain normal blood glucose concentration Glucose can be converted Glycogen Fatty acids 5 carbon sugars Amino acids H2O, CO2 and ATP 27-Apr-19 Liver Functions

Fat Metabolism - oxidation of FFA Acetocetic acid Formation of lipoproteins Formation of cholesterol and phopholipids For cell membrane formation Bile formation Cholesterol is precursor for some hormones Conversion of dietary sugars & AA Fatty acids 27-Apr-19 Liver Functions

Protein Metabolism Synthesis of Enzymes Plasma proteins Essential for hepatocyte function Plasma proteins Transport proteins (albumin, transferrin, ceruloplasmin, haptoglobulin) Other proteins (clotting factors, complement factors) Acute phase reactant proteins 27-Apr-19 Liver Functions

Protein Metabolism Deamination of amino acids Before they can be Used for energy Converted into carbohydrates or fat Formation of UREA Removal of ammonia 27-Apr-19 Liver Functions