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Physiology 1 > The Liver: An Intro To Its function > Flashcards

The Liver: An Intro To Its function Flashcards

1
Q

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

A

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

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2
Q

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

A

2- falciform ligament

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3
Q

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

A

Portal vein

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4
Q

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

A

Hepatic artery (straight from the aorta)

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5
Q

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

A

Hepatic vein and back to the inferior vena cava

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6
Q

What are the types of cells in the liver?

A 
Hepatocytes (60%)
Kupffer cells (30%)
Liver endothelial and Stellate cells
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7
Q

What function do hepatocytes carry out?

A

Most metabolic functions

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8
Q

What functions do kupffer cells carry out?

A

Clear gut derived endotoxins from the blood in the portal vein

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9
Q

What is the functional unit in the liver?

A

Hepatic lobule

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10
Q

What are the hepatic lobules?

A

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

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11
Q

How does the microstructure of the liver support its roles?

A

Huge SA for exchange of molecules

Sophisticated separation of blood from bile

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12
Q

What do kupffer cells function as?

A

A mononuclear phagocyte system

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13
Q

Where are kupffer cells found?

A

In sinusoids

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14
Q

What lines the lumen of the sinusoid?

A

Liver sinusoidal epithelial cells

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15
Q

What is behind the liver sinusoidal epithelial cells?

A

Perisinusoidal space

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16
Q

What is in bile?

A

Water, electrolytes and organic molecules

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17
Q

What organic molecules are in bile?

A

Bile acids, cholesterol, bilirubin and phospholipids

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18
Q

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

A

400-800 ml

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19
Q

What are the two stages of bile secretion?

A

Hepatocytes synthesise the organic constituents

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

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20
Q

Describe the enterohepatic circulation of bile acids

A

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

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21
Q

How are the bile salts transported into the duodenum?

A

Active transport into the bile cannuliculi by ATP dependent transporters

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22
Q

How are bile salts deconjugated into primary bile acids?

A

Loosing a glycine or taurine

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23
Q

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

A

Intestinal bacteria

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24
Q

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

A

5%

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25
Q

How is bile formation controlled?

A

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

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26
Q

What is the physiological significance of bile?

A
  • emulsification of fats
  • neutralise gastric juice
  • Eliminate waste products like bilirubin and cholesterol
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27
Q

What causes gallstone formation?

A

Inbalance in the chemical makeup of bile inside the gallbladder

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28
Q

What are the two types of gallstones and their prevalence?

A

Cholesterol (80%) or pigment (20%)

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29
Q

What are the risk factors for cholesterol gallstones?

A

High fat diet and increased cholesterol synthesis

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30
Q

Why are cholesterol gallstones formed?

A

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

31
Q

What are the risk factors for gallstones?

A

Women, obesity, excess oestrogen, hormone replacement therapy

32
Q

Why are pigment gallstones formed?

A

Excess breakdown of RBCs into bilirubin

33
Q

Where can gallstones form?

A

Anywhere along the biliary tract

34
Q

What is bilirubin?

A

Yellow pigment formed from the breakdown of haemoglobin

35
Q

Why must bilirubin be removed?

A

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

36
Q

Where are senescent RBCs broken down?

A

Spleen

37
Q

What is haemoglobin broken down into?

A

Haem and globin

38
Q

What does haem oxygenase break down haem into?

A

Bilivirdin

39
Q

What enzyme catalyses bilivirdin -> bilirubin?

A

Bilivirdin reductase

40
Q

What is unconjugated bilirubin bound to?

A

Albumin

41
Q

Where is the unconjugated bilirubin transported?

A

Liver

42
Q

What happens to the unconjugated bilirubin in the liver?

A

Conjugated with glucuronic acid and then secreted into bile

43
Q

What converts bilirubin into urobilinogen?

A

Intestinal bacteria

44
Q

What happens after the urobilinogen is formed?

A

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

45
Q

What causes jaundice?

A

When plasma bilirubin concentration exceeds 1.5 mg/day

46
Q

What are the three groups of jaundice?

A

Prehepatic (haemolytic)
Hepatic
Post hepatic (obstructive)

47
Q

What causes prehepatic jaundice?

A

Excessive breakdown of RBCs or an excess of conjugated bilirubin

48
Q

What causes hepatic jaundice?

A

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

49
Q

What causes post hepatic jaundice?

A

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

50
Q

What are sunlight canopies and what do they do?

A

Help with neonatal jaundice in global south countries

Filters out most light rays, to allow the therapeutic blue light to pass through

51
Q

What is the use of blue light in jaundice?

A

Conjugates unconjugated bilirubin into conjugated bilirubin

52
Q

What are the blood clotting factors?

A

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

53
Q

Why is vitamin K essential?

A

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

54
Q

What does warfarin do?

A

Blocks oxidised vitamin k -> vitamin K

55
Q

What’s stored in hepatocytes?

A

Vitamins A, D, E and K

56
Q

How much vitamin B12 does the average person have stored?

A

Enough to last 2-3 years

57
Q

What does a vitamin B12 deficiency lead to?

A

Pernicious anaemia

58
Q

When is folate required?

A

Early pregnancy

59
Q

Where is folate stored?

A

Liver

60
Q

What is iron stored as in the liver?

A

Ferritin

61
Q

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

A

Bilirubin, ammonia, hormones, drugs and exogenous toxins

62
Q

What is gynaecomastia?

A

Breast enlargement in males due to alcoholic cirrhosis

63
Q

What phase of development are adult hepatocytes in normally?

A

G0

64
Q

How much liver is removed in a partial hepatectomy?

A

70%

65
Q

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

A

Rapidly reenter the cell cycle and proliferate

66
Q

When does proliferation of new liver tissue stop?

A

Once the original mass of the liver is reestablished

67
Q

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

A
  • 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
68
Q

What do liver function tests do?

A

Check the levels of certain enzymes and proteins in the blood

69
Q

What can liver function tests be used to measure?

A
  • Progression of a disease and how well a treatment is working
  • severity of a disease- scarring of the liver
  • possible side effects of medications
70
Q

What does a high alanine aminotransferase or aspartate aminotransferase mean?

A

Hepatitis or alcohol induced Liver damage

71
Q

What does high alkaline phosphatase levels indicate?

A

Obstruction in bile flow

72
Q

What does high gamma gutamyl transverase levels indicate?

A

Obstruction in bile flow

73
Q

What does high bilirubin levels indicate?

A

Jaundice

74
Q

What do low albumin levels indicate?

A

Chronic liver disease/ malnutrition

Physiology 1 (65 decks)

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