Liver Structure + Function

Question 1

What percentage of blood entering the liver is oxygenated and which vessel carries it?

Answer 1

25% through the hepatic artery

Question 2

What is the portal triad?

Answer 2

branches of the hepatic artery, hepatic portal vein and bile duct.

Question 3

What are sinusoids?

Answer 3

Small vessels between liver cells in lobules running into central venule, then hepatic vein.

Question 4

What are bile canaliculi?

Answer 4

Small tubes that bile from cells flows down into the bile ducts

Question 5

What is the Space of Disse?

Answer 5

Between the hepatocytes and the endothelial cells runs the Space of Disse. This contains stellate cells and collagen fibres

Question 6

What are Kupffer cells?

Answer 6

Kupffer cells act as a ‘sieving system’ to prevent antigens reaching the rest of the body.
Located within sinusoidal lining – macrophages. Phagocytose bacteria, old erythrocytes, protect liver from gut derived bacteria etc.

Question 7

What are pit cells?

Answer 7

Natural killer cells – help protect liver from viruses/tumour cells

Question 8

What are hepatic stellate cells?

Answer 8

Lipid-filled cells. Primary site of vitamin A storage. Also control turnover of connective tissue, synthesise collagen & regulate contractility of sinusoids

Question 9

Two main functions of the liver

Answer 9

The Factory:
carbohydrate, lipid and protein metabolism
bile formation

Waste Management:
detoxification of xenobiotics
removal of internal waste e.g.
degradation of bilirubin

Question 10

What does bile contain?

Answer 10

water, bicarbonate, bile salts, cholesterol, phospholipids

Question 11

What are either primary or secondary bile acids conjugated with?

Answer 11

Glycine or Taurine.

Question 12

How can you increase the excretion of bile salts?

Answer 12

Increase fibre intake - more excretion

Cholestyramine drug - binds bile acids in the gut
prevents recirculation of bile
increases bile acid synthesis
decreases blood cholesterol

Question 13

How do gallstones occur?

Answer 13

If more cholesterol enters the bile than can be solubilised by bile salts – precipitation of cholesterol occurs

Question 14

How does acute cholecystitis happen?

Answer 14

When a gallstone gets stuck in the bile duct or cystic duct.

Question 15

What are xenobiotics?

Answer 15

compounds potentially toxic, and of no nutritional value

e.g drugs or food additives

Question 16

What are 3 features of phase 1 metabolism?

Answer 16

mainly performed by cytochrome P450 enzymes (CYP)

large family of haem proteins – mono-oxygenases

found in smooth endoplasmic reticulum

Question 17

What are 3 features of phase 2 metabolism?

Answer 17

Conjugation – addition of glucuronyl, sulphate, methyl, acetyl, glycyl groups to reactive group on molecule

Various enzymes involved

Many of these reactions occur in liver, but also lung, kidney

Question 18

What is alcohol broken down into?

Answer 18

Acetate, using dehydrogenases

Question 19

What are RBCs mainly phagocytosed by?

Answer 19

Kupffer cells.

Question 20

What happens to the haem molecule in haemoglobin when it is broken down?

Answer 20

Haem>biliverdin>bilirubin

Question 21

What happens to the bilirubin?

Answer 21

It is transported to the liver hepatocytes attached to albumin
where it is conjugated with glucuronic acid and secreted into the bile canalicula.

In the gut it’s converted to urobilinogen.
Urobilinogen is converted into urobilin (in urine) and stercobilin (in faeces)

Question 22

What is jaundice?

Answer 22

If there are problems with haem degradation jaundice occurs – deposition of bilirubin in tissues.

Question 23

What are the 3 types of jaundice?

Answer 23

Prehepatic jaundice - e.g sickle cell

Intrahepatic jaundice - e.g Gilbert’s syndrome

Extrahepatic jaundice - e.g gallstones