Liver Flashcards
What is the blood supply to the hepatocytes of the liver?
Dual blood supply:
Hepatic artery 20%
Hepatic portal vein 80%
Describe the structure of the liver
- organised into lobules: each contain a hepatic portal triad at each of the 6 corners
- made up of hepatocytes which have a dual blood supply from the heptaic portal vein + hepatic artery
- venous + arterial blood mix in the hepatic sinusoids
- bile canaliculli carry bile + merge to form bile ducts
What is the hepatic triad made of?
Hepatic portal vein
Hepatic artery
Bile duct
Difference between hepatic portal vein + hepatic vein
- hepatic portal vein brings blood TO the liver
- hepatic vein takes blood AWAY FROM the liver
What is the functional unit of the liver?
Acinus
Describe the acinus of the liver
- diamond shape of adjoining liver lobules
- contains three zones: zone 1 is closest to portal triad | zone 3 closest to central vein
- toxins effect zone 1 most
- ischemic damage effects zone 3 most
What part of the liver acinus do toxins effect the most?
Zone 1
What part of the liver acinus does ischemic damage effect the most?
Zone 3
What are the two components of bile?
Bile acid dependant
Bile acid independent
Outline the bile acid dependant component of bile
- secreted into canaliculi by hepatocytes
- contains bile acids + pigments
Outline the bile acid independent component of bile
- secreted by duct cells
- alkaline solution (like pancreatic duct cells)
- stimulated by secretin
Function of bile acids
Important in digesting fats
What are the 2 primary bile acids?
Cholic acid
Chenodeoxychloic acid
Function of bile salts
Helps solubilise fats
Facilitate fat digestion - form micelles
What are bile salts?
Bile acids which are conjugated with amino acids e.g. glycine + turbine
Why do we need bile salts as well as bile acids?
- bile acids are not always soluble at duodenal pH > bile salts generally are soluble
- bile salts have amphipathic structure > can act at oil/water interface > crucial for emulsification of dietary lipids
Describe the digestion of fats
- bile acids emulsify fats into smaller units > increases SA
- bile salts form micelles with lipid breakdown products
- allows fats to diffuse to brush border of enterocyte
- lipids diffuse down conc. gradient into cytosol of enterocyte
- lipids are re-esterified back into tri-glycerides, phospholipids + cholesterol
- reformed lipids packaged with apoproteins to form chylomicrons
- chylomicrons exocytose + enter lymph capillaries > thoracic duct > left internal jugular vein
What happens to bile salts after aiding fat digestion?
- remain in gut lumen
- reabsorbed in terminal ileum
- return to liver in portal blood
- liver extracts bile salts to reuse
Where is bile stored?
Gallbladder
Where is bile produced?
Hepatocytes
What is steatorrhoea?
Excretion of excess amounts of fat in faeces
Symptoms of steatorrhoea
Faeces are:
Foul smelling
Pale
Hard to flush
Float
How many lobes does the liver have?
Name them
4 lobes
Left lobe
Right lobe
Caudate lobe - next to IVC
Quadrate lobe - next to gall bladder
What peritoneal ligaments attach the liver to the diaphragm?
Falciform ligament
Coronal ligament
Triangular ligament - ‘at the corners/points’
What is the bare area of the liver?
Part of the liver with no peritoneal covering on right lobe
Where does the hepatic portal vein originate?
Behind the neck of the pancreas L1
What drains into the hepatic portal vein?
Splenic vein
Superior mesenteric vein
Describe the anatomical location of the portal triad in relation to the vessels
- Bile duct lateral
- Hepatic artery medial
- Hepatic portal vein posterior
Portal - Posterior
biLe - Lateral
