The Liver: An Intro To Its function

Question 1

What are the major function influencing structural features in the liver?

Answer 1

Vascular system, biliary tree, 3D arrangement of liver cells with the vascular and biliary system

Question 2

How many lobes are in the liver and what are they divided by?

Answer 2

2- falciform ligament

Question 3

Where does 75% of the blood supply to the liver come from?

Answer 3

Portal vein

Question 4

Where does the other 25% of liver blood supply come from?

Answer 4

Hepatic artery (straight from the aorta)

Question 5

Where do the central veins of the liver lobules drain into?

Answer 5

Hepatic vein and back to the inferior vena cava

Question 6

What are the types of cells in the liver?

Answer 6

Hepatocytes (60%)
Kupffer cells (30%)
Liver endothelial and Stellate cells

Question 7

What function do hepatocytes carry out?

Answer 7

Most metabolic functions

Question 8

What functions do kupffer cells carry out?

Answer 8

Clear gut derived endotoxins from the blood in the portal vein

Question 9

What is the functional unit in the liver?

Answer 9

Hepatic lobule

Question 10

What are the hepatic lobules?

Answer 10

Hexagonal plates of hepatocytes around the central hepatic vein
At each corner there is a portal vein, hepatic artery and bile duct

Question 11

How does the microstructure of the liver support its roles?

Answer 11

Huge SA for exchange of molecules

Sophisticated separation of blood from bile

Question 12

What do kupffer cells function as?

Answer 12

A mononuclear phagocyte system

Question 13

Where are kupffer cells found?

Answer 13

In sinusoids

Question 14

What lines the lumen of the sinusoid?

Answer 14

Liver sinusoidal epithelial cells

Question 15

What is behind the liver sinusoidal epithelial cells?

Answer 15

Perisinusoidal space

Question 16

What is in bile?

Answer 16

Water, electrolytes and organic molecules

Question 17

What organic molecules are in bile?

Answer 17

Bile acids, cholesterol, bilirubin and phospholipids

Question 18

How much bile does the average adult produce in a day?

Answer 18

400-800 ml

Question 19

What are the two stages of bile secretion?

Answer 19

Hepatocytes synthesise the organic constituents

Epithelial cells lining the bile ducts secrete large quantities of watery solution

Question 20

Describe the enterohepatic circulation of bile acids

Answer 20

Cholesterol -> primary bile acids -> bile salts -> duodenum where its deconjugated into primary bile acids -> broken down into secondary bile acids -> reabsorbed into circulation in the small intestine

Question 21

How are the bile salts transported into the duodenum?

Answer 21

Active transport into the bile cannuliculi by ATP dependent transporters

Question 22

How are bile salts deconjugated into primary bile acids?

Answer 22

Loosing a glycine or taurine

Question 23

How are primary bile acids broken down into secondary bile acids?

Answer 23

Intestinal bacteria

Question 24

What % of secondary bile acids are lost in the faeces?

Answer 24

5%

Question 25

How is bile formation controlled?

Answer 25

Negative feedback mechanism -> too much bile means bile synthesis is inhibited

Question 26

What is the physiological significance of bile?

Answer 26

- emulsification of fats - neutralise gastric juice - Eliminate waste products like bilirubin and cholesterol

Question 27

What causes gallstone formation?

Answer 27

Inbalance in the chemical makeup of bile inside the gallbladder

Question 28

What are the two types of gallstones and their prevalence?

Answer 28

Cholesterol (80%) or pigment (20%)

Question 29

What are the risk factors for cholesterol gallstones?

Answer 29

High fat diet and increased cholesterol synthesis

Question 30

Why are cholesterol gallstones formed?

Answer 30

If the gallbladder epithelium is inflamed it changes the absorptive characteristic of the mucosa so cholesterol concentrates

Question 31

What are the risk factors for gallstones?

Answer 31

Women, obesity, excess oestrogen, hormone replacement therapy

Question 32

Why are pigment gallstones formed?

Answer 32

Excess breakdown of RBCs into bilirubin

Question 33

Where can gallstones form?

Answer 33

Anywhere along the biliary tract

Question 34

What is bilirubin?

Answer 34

Yellow pigment formed from the breakdown of haemoglobin

Question 35

Why must bilirubin be removed?

Answer 35

Toxic and made in large quantities (6g/day)

Question 36

Where are senescent RBCs broken down?

Answer 36

Spleen

Question 37

What is haemoglobin broken down into?

Answer 37

Haem and globin

Question 38

What does haem oxygenase break down haem into?

Answer 38

Bilivirdin

Question 39

What enzyme catalyses bilivirdin -> bilirubin?

Answer 39

Bilivirdin reductase

Question 40

What is unconjugated bilirubin bound to?

Answer 40

Albumin

Question 41

Where is the unconjugated bilirubin transported?

Answer 41

Liver

Question 42

What happens to the unconjugated bilirubin in the liver?

Answer 42

Conjugated with glucuronic acid and then secreted into bile

Question 43

What converts bilirubin into urobilinogen?

Answer 43

Intestinal bacteria

Question 44

What happens after the urobilinogen is formed?

Answer 44

It’s reabsorbed into the portal vein and excreted in urine or turned into stercobolin and excreted in faeces

Question 45

What causes jaundice?

Answer 45

When plasma bilirubin concentration exceeds 1.5 mg/day

Question 46

What are the three groups of jaundice?

Answer 46

Prehepatic (haemolytic) Hepatic Post hepatic (obstructive)

Question 47

What causes prehepatic jaundice?

Answer 47

Excessive breakdown of RBCs or an excess of conjugated bilirubin

Question 48

What causes hepatic jaundice?

Answer 48

Damaged hepatocytes which leads to an excess of conjugated and/or unconjugated bilirubin

Question 49

What causes post hepatic jaundice?

Answer 49

Excess conjugated bilirubin due to an obstruction in the duodenum so it enters the circulation and urine

Question 50

What are sunlight canopies and what do they do?

Answer 50

Help with neonatal jaundice in global south countries Filters out most light rays, to allow the therapeutic blue light to pass through

Question 51

What is the use of blue light in jaundice?

Answer 51

Conjugates unconjugated bilirubin into conjugated bilirubin

Question 52

What are the blood clotting factors?

Answer 52

Fibrinogen, prothrombin, basically all other factors (V, VI, IX, X, XII)

Question 53

Why is vitamin K essential?

Answer 53

Converts prothrombin and factors II, VII, IX and X into their functional forms

Question 54

What does warfarin do?

Answer 54

Blocks oxidised vitamin k -> vitamin K

Question 55

What’s stored in hepatocytes?

Answer 55

Vitamins A, D, E and K

Question 56

How much vitamin B12 does the average person have stored?

Answer 56

Enough to last 2-3 years

Question 57

What does a vitamin B12 deficiency lead to?

Answer 57

Pernicious anaemia

Question 58

When is folate required?

Answer 58

Early pregnancy

Question 59

Where is folate stored?

Answer 59

Liver

Question 60

What is iron stored as in the liver?

Answer 60

Ferritin

Question 61

What are the four (groups of) things the liver metabolises?

Answer 61

Bilirubin, ammonia, hormones, drugs and exogenous toxins

Question 62

What is gynaecomastia?

Answer 62

Breast enlargement in males due to alcoholic cirrhosis

Question 63

What phase of development are adult hepatocytes in normally?

Answer 63

G0

Question 64

How much liver is removed in a partial hepatectomy?

Answer 64

70%

Question 65

What happens to the surviving adult hepatocytes after a partial hepatectomy or a toxic injury?

Answer 65

Rapidly reenter the cell cycle and proliferate

Question 66

When does proliferation of new liver tissue stop?

Answer 66

Once the original mass of the liver is reestablished

Question 67

What are the two pathways that have been hypothesised for regeneration of the liver?

Answer 67

- growth factor mediated pathway -> most important HGF and TGF alpha - cytokine signalling pathway using ILG vie TNF alpha binding to its receptor on kupffer cells

Question 68

What do liver function tests do?

Answer 68

Check the levels of certain enzymes and proteins in the blood

Question 69

What can liver function tests be used to measure?

Answer 69

- Progression of a disease and how well a treatment is working - severity of a disease- scarring of the liver - possible side effects of medications

Question 70

What does a high alanine aminotransferase or aspartate aminotransferase mean?

Answer 70

Hepatitis or alcohol induced Liver damage

Question 71

What does high alkaline phosphatase levels indicate?

Answer 71

Obstruction in bile flow

Question 72

What does high gamma gutamyl transverase levels indicate?

Answer 72

Obstruction in bile flow

Question 73

What does high bilirubin levels indicate?

Answer 73

Jaundice

Question 74

What do low albumin levels indicate?

Answer 74

Chronic liver disease/ malnutrition