Normal Liver Physiology

Question 1

What are the main roles of the liver?

Answer 1

Metabolism (glucose and lipid)
Absorption of fat (via bile production)
Protein synthesis (plasma proteins, lipoproteins)
Storage (iron, vitamins)
Detoxification

Question 2

Describe 4 characteristic features of the hepatocyte and their roles

Answer 2

Prominent rough ER, Golgi complexes and secretory vesicles: protein synthesis
Prominent smooth ER: fat and steroid metabolism
Many mitochondria
1-2 nuclei

Question 3

How is the liver parenchyma organised?

Answer 3

Lobules around blood vessels (hepatitic artery and portal vein)
Hepatocytes supported by reticular fibres with collagen I/III

Question 4

What structures are in the portal triad?

Answer 4

Hepatic artery
Hepatic portal vein
Bile duct
Lymphatics

Question 5

Describe the direction of flow in the lobule

Answer 5

Outside in (from triads towards central vein)

Question 6

What are the sinusoids?

Answer 6

Specialised fenestrated capillaries converging on the central vein

Question 7

What is the space of Disse?

Answer 7

Gap between endothelium and adjacent hepatocyte

Question 8

Where do the macrophages reside in the liver?

Answer 8

Kupffer cells on the inner walls of the sinusoids

Question 9

Contrast the classic, portal and acinar lobule models

Answer 9

Classic: central vein is centre, focus on direction of blood flow
Portal: portal triad is central, focus on direction of bile flow
Acinar: physiological zones

Question 10

Describe the physiological zones in the acinar lobule model

Answer 10

Zone 1: closest to portal triad, high in O2/toxins/nutrients

Zone 3: closest to central vein, low in toxins/metabolites

Question 11

Describe the flow of bile through the liver

Answer 11

Collects in canaliculi

Flows outwards to be collected in bile ducts in portal triads

Question 12

What kind of epithelium is in the gall bladder?

Answer 12

Simple absorptive

Question 13

Describe the structure of bilirubin

Answer 13

Open chain of four pyrole rings (tetrapyrole)

Question 14

Describe the mononuclear phagocyte system (reticuloendothelial system)

Answer 14

Monocytes and macrophages in LNs and spleen (+ Kupffer cells in liver) primarily responsible for destruction of RBCs

Question 15

How are old RBCs recognised by the mononuclear phagocyte system?

Answer 15

Surface changes (e.g. exposure of phosphatidyl serine, reduced sialic acid) coated with Abs or recognised directly