Liver

Question 1

What is the blood supply to the hepatocytes of the liver?

Answer 1

Dual blood supply:
Hepatic artery 20%
Hepatic portal vein 80%

Question 2

Describe the structure of the liver

Answer 2

• 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

Question 3

What is the hepatic triad made of?

Answer 3

Hepatic portal vein
Hepatic artery
Bile duct

Question 4

Difference between hepatic portal vein + hepatic vein

Answer 4

• hepatic portal vein brings blood TO the liver
• hepatic vein takes blood AWAY FROM the liver

Question 5

What is the functional unit of the liver?

Answer 5

Acinus

Question 6

Describe the acinus of the liver

Answer 6

• 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

Question 7

What part of the liver acinus do toxins effect the most?

Answer 7

Zone 1

Question 8

What part of the liver acinus does ischemic damage effect the most?

Answer 8

Zone 3

Question 9

What are the two components of bile?

Answer 9

Bile acid dependant
Bile acid independent

Question 10

Outline the bile acid dependant component of bile

Answer 10

• secreted into canaliculi by hepatocytes
• contains bile acids + pigments

Question 11

Outline the bile acid independent component of bile

Answer 11

• secreted by duct cells
• alkaline solution (like pancreatic duct cells)
• stimulated by secretin

Question 12

Function of bile acids

Answer 12

Important in digesting fats

Question 13

What are the 2 primary bile acids?

Answer 13

Cholic acid
Chenodeoxychloic acid

Question 14

Function of bile salts

Answer 14

Helps solubilise fats
Facilitate fat digestion - form micelles

Question 15

What are bile salts?

Answer 15

Bile acids which are conjugated with amino acids e.g. glycine + turbine

Question 16

Why do we need bile salts as well as bile acids?

Answer 16

• 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

Question 17

Describe the digestion of fats

Answer 17

• 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

Question 18

What happens to bile salts after aiding fat digestion?

Answer 18

• remain in gut lumen
• reabsorbed in terminal ileum
• return to liver in portal blood
• liver extracts bile salts to reuse

Question 19

Where is bile stored?

Answer 19

Gallbladder

Question 20

Where is bile produced?

Answer 20

Hepatocytes

Question 21

What is steatorrhoea?

Answer 21

Excretion of excess amounts of fat in faeces

Question 22

Symptoms of steatorrhoea

Answer 22

Faeces are:
Foul smelling
Pale
Hard to flush
Float

Question 23

How many lobes does the liver have?
Name them

Answer 23

4 lobes
Left lobe
Right lobe
Caudate lobe - next to IVC
Quadrate lobe - next to gall bladder

Question 24

What peritoneal ligaments attach the liver to the diaphragm?

Answer 24

Falciform ligament
Coronal ligament
Triangular ligament - ‘at the corners/points’

Question 25

What is the bare area of the liver?

Answer 25

Part of the liver with no peritoneal covering on right lobe

Question 26

Where does the hepatic portal vein originate?

Answer 26

Behind the neck of the pancreas L1

Question 27

What drains into the hepatic portal vein?

Answer 27

Splenic vein Superior mesenteric vein

Question 28

Describe the anatomical location of the portal triad in relation to the vessels

Answer 28

- **Bile duct** lateral - **Hepatic artery** medial - **Hepatic portal vein** posterior **P**ortal - **P**osterior bi**L**e - **L**ateral