Liver Physiology

Question 1

What is the blood supply to the liver?

Answer 1

30% Hepatic artery

70% Portal vein

Question 2

What major veins drain into the portal vein?

Answer 2

Superior mesenteric vein and splenic vein

Question 3

What are the major cell types of the liver?

Answer 3

Hepatocytes
Cholangiocytes
Endothelial cells
Kupffer cells
Lipocytes (Stellate cells)

Question 4

What are the functions of the liver? (Hint: DESPICES)

Answer 4

Drug metabolism and detoxification
Energy metabolism and substrate interconversion - (glucose, glycolysis, urea)
Synthesis of plasma proteins (albumin, fibrinogen, plasminogen)
Production of bile
Immune function - kupffer cells (phagocytosis)
Cholesterol processing
Excretion of bilirubin
Storage of vit and min (A,D,E,K/ iron, copper)

Question 5

How much bile does the liver produce per day? What does the gall bladder do?

Answer 5

0.7-1.2 L daily
Stores and concentrates bile
Liver secretes bile - drains into main bile duct

Question 6

What is bile composed of? (Hint: Be Happy That Liver Creates Bile)

Answer 6

Bile salts (solubilise fat in SI)
HCO3- (neutralise acid in duodenum)
Trace metals
Lecithin (emulsifier)
Cholesterol
Bile pigments (bilirubin)

Question 7

Are bile salts lost or recycled?

Answer 7

Released into SI
95% recycled - enterohepatic circulation - back to liver
5% lost in faeces

Question 8

What are the main functions of bile salts?

Answer 8

Emulsification of dietary lipids (panc lipase can now access)
Elimination of cholesterol
Prevents cholesterol precipitations in the gall bladder (gall stones)
Absorption of vit D, E, A, K, iron, copper

Question 9

What are the functions of cholesterol?

Answer 9

Plasma membrane
component of bile salts
precursor of steroid hormones
myelin sheath

Question 10

Where does cholesterol come from?

Answer 10

15% - diet
85% - synthesised
Transported in complexes with lipoproteins

Question 11

How does the liver process cholesterol?

Answer 11

Synthesises chol from acetyl coA
Syntehsises lipoproteins
Exports chol via circulatory system to body cells
Exports chol to liver for bile salt synthesis
Extracts excess chol from plasma
Export excess chol via liver into bile for excretion into faeces

Question 12

How is bilirubin formed?

Answer 12

Breakdown of haem in the spleen and bone marrow