The Liver

What is the liver?

The largest visceral organ

Where is the liver located?

• It lies in the right hypochondriac and epigastric regions

• It extends to the left hypochondriac and umbilical regions

What does the liver do?

Performs essential metabolic and synthetic functions

What is the anatomy of the liver?

• It is wrapped in tough fibrous capsule

• It is covered by visceral peritoneum

• It is divided into lobes

Where does the liver receives blood from?

• 2/3 from the hepatic portal vein

• 1/3 from the hepatic artery proper

Where does the hepatic portal vein originate from?

The oesophagus, stomach, small intestine, and much of the large intestine. The other 1/3 of blood is received from the hepatic artery proper

What is the histology of the liver?

• ~100,000 hexagonal lobules (functional unit of liver) = 1mm in diameter

• Hexagonal in cross section with six portal areas (portal triads)

• Portal areas contain: branch of hepatic portal vein, branch of hepatic artery proper, branch of bile duct

• Blood flows past hepatocytes which absorb solutes and secrete proteins

• Drains into: sinusoids → central vein, bile ductules → bile ducts

What are the metabolic regulation functions of the liver?

• Metabolism of carbohydrate (stabilises glucose, glycogen store, glycogenesis)

• Metabolism of lipids (regulates circulating triglycerides, fatty acids, cholesterol)

• Metabolism of amino acids (storage, deamination)

• Waste product removal (neutralises ammonia and other toxins)

• Vitamin storage (fat soluble vitamins (A, D, E, K), B12)

• Mineral storage (ferritin)

• Drug inactivation

What are the haematological regulation functions of the liver?

• Phagocytosis and antigen presentation

• Synthesis of plasma proteins

• Removal of circulating hormones, antibodies, toxins

What is the bile production function of the liver?

• Bile salts break insoluble lipid droplets apart (emulsification)

• Increases surface area exposed to enzymatic attack

What does the liver look like?