Liver Structure & Function Flashcards
What is the structure of the liver?
Structure:
Left & right lobes
Caudate lobe
Quadrate lobe
Falciform ligament
Lesser omentum (Hepatoduodenal ligament)
Hepatic hilum
Portal triad at corner of each lobule (portal vein, hepatic artery, hepatic ducts)
Central veins at centre of each lobule - Hepatic veins - IVC
What is the histology of the liver?
Histology:
- Liver covered by connective tissue capsule and visceral peritoneum (except bare area on diaphragmatic surface surrounded by coronary ligament)
- Hepatic cords radiate out from central veins
- Hepatic cords are made up of hepatocytes, which are the functional units of the liver
- Between the hepatic cords lie the Bile canaliculus which collects the bile
What is the function of the liver?
Production and secretion of Bile
All the components of bile are produced by the liver, except bicarbonate which is produced by the duct cells of the Pancreas
What is the function and composition of bile?
Function - digestion and absorption of fats and fat soluble vitamins from the small intestine
Composition:
Bile acids (produced by hepatocytes)
Lecithin (produced by hepatocytes)
Cholesterol (produced by hepatocytes)
Bile pigments (haemoglobin)
Toxic metals
Bicarbonate (produced by duct cells)
What are the mechanisms controlling the storage and release of bile from the gallbladder?
Sphincter of Oddi controls release of bile and pancreatic juice into Duodenum
Secretion:
1) When fat arrives in Duodenum, this stimulates the release of CCK which relaxes the sphincter of oddi and contracts the gallbladder which forces out the bile into the duodenum
2) Bile in the duodenum leads to solubilisation of fat
Storage:
1) When Sphincter of Oddi contracted, the bile is forced back into the gallbladder
2) The Gallbladder can concentrate bile by 5-20 times by removing Na+ and water
How is bile reabsorbed?
Enterohepatic circulation:
1) Liver
2) Bile duct
3) Duodenum
4) Ileum
5) Portal vein
6) Back to Liver
