Liver Function Tests

A right and a left lobe Sheets of hepatocytes embedded in capillary network The liver has a dual blood supply - the portal vein and the hepatic artery The liver has a huge regenerative capacity

It brings blood to the liver from GIT (low oxygen: high nutrients)

It supplies the liver with oxygen

Synthesis Storage Detoxification and excretion Metabolism

Carbohydrates Proteins Bile acids Fatty acids Cholesterol Lipoproteins Active vitamin D (calcitriol) Clotting factors

The liver uses glucose for its own cellular energy The liver circulates glucose to peripheral tissue The liver stores glucose as glycogen The liver is a major player in maintaining stable glucose concentration due to glycogenesis, glycogenolysis and gluconeogenesis Thus the liver is responsible for the synthesis, storage and release of glucose

The liver gathers free fatty acids from diet and breaks them down to Acetyl-CoA to form triglycerides, phospholipids or cholesterol It converts insoluble lipids to soluble forms The liver produces 70% pf cholesterol It synthesises HDL, LDL and VLDL Thus both degradation and synthesis of fats takes place in the liver

It breaks them down to Acetyl-CoA

HDL LDL VLDL

It converts insoluble forms to soluble forms

70%

The liver produces nearly all proteins bar immunoglobulins and haemoglobin The liver synthesises enzymes and clotting factors

The liver has an immune function, Kupffer cells which serve as a gatekeeper between the circulation and absorbed substances The liver detoxifies drugs and poisons and metabolic products like ammonia, alcohol and bilirubin The liver can inactivate hormones such as cortisol, aldosterone, insulin, glucagon and testosterone

Kuppfer cells

Drugs Poisons Ammonia Alcohol Bilirubin

Cortisol Aldosterone Insulin Glucagon Testosterone

By binding to material to reversibly inactive them By chemically modifying compounds for excretion Drug metaboliser for detoxification of drugs and poisons

Ammonia must be carefully controlled because its toxic to the CNS and is freely permeable across the blood brain barrier The liver is the only organ in which the complete Krebs cycle is expressed In this ammonia is converted to urea which is much less toxic, water soluble and easily excreted in urine

Urea

Glycogen Proteins Vitamins A, B12 and C Iron

Bile is important for fat digestion and is also a route of excretion from the body Bile consists of water, bile salts, cholesterol, phospholipids, electrolytes and bile pigments which give its typical yellowy-green colour Bile is made up of bile salts, bile pigments and other substances dissolved in alkaline electrolyte solution Metabolic wastes and drug products may form part of the bile which can be excreted from the body through the digestive tract in the faeces e.g. bilirubin, the toxic end product of haemoglobin breakdown is excreted from the body in this way

Bile consists of water, bile salts, cholesterol, phospholipids, electrolytes and bile pigments which give its typical yellowy-green colour Bile is made up of bile salts, bile pigments and other substances dissolved in alkaline electrolyte solution

Metabolic wastes and drug products may form part of the bile which can be excreted from the body through the digestive tract in the faeces e.g. bilirubin, the toxic end product of haemoglobin breakdown is excreted from the body in this way

Jaundice Portal hypertension Bleeding oesophageal varices Ascites Altered drug metabolism Liver failure