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BRS (Bioregulatory Systems) > Hepatobiliary system > Flashcards

Hepatobiliary system Flashcards

1
Q

Where does the liver reside in relation to the diaphragm?

A

Inferior to the cdiapjgram, in the upper right quadrant of the abdominal cavity. Liver is divided into two primary lobes, right and left

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2
Q

What are the two primary lobes of the liver?

A

Right and left

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3
Q

Which folds connect the liver to the abdominal wall and diaphragm?

A

Pertioneal folds (ligaments)

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4
Q

What is the falciform ligament?

A

The falciform ligaments runs inferiorly from the diaphragm across the anterior edge of the liver to its inferior border. At the inferior end of the liver, the falciform ligament forms the ligamentum teres of the liver.

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5
Q

What are the four lobes of the liver?

A

Left, right caudate, and quadrate

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6
Q

What ligament separates the right and left lobe?

A

The falciform ligament

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7
Q

Where is the caudate lobe located within the liver?

A

Posterior side of the right lobe, wraps around the inferior vena cava

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8
Q

Where is the quadrate lobe in relation to the caudate lobe?

A

The quadrate lobe is inferior the the caudate, wrapping around the gallbladder.

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9
Q

Which lobe wraps around the gallbladder?

A

The quadrate lobe

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10
Q

Which part of the lobe does the hepatic artery and hepatic portal veins enter?

A

Porta hepatis

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11
Q

What vessel delivers the majority of blood to the liver?

A

Hepatic portal veins

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12
Q

Which vessels deliver blood to the liver?

A

Hepatic portal veins

Hepatic artery

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13
Q

What % of blood flow arises from the hepatic artery into the liver?

A

25%

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14
Q

What is the hepatic artery?

A

Delivers oxygenated blood from the heart to the liver

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15
Q

What is the hepatic portal vein?

A

Delivers partially deoxygenated blood containing nutrients and toxins absorbed from the small intestine, pancreas, gall bladder and spleen to the liver

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16
Q

What is the main outflow of the liver?

A

There are 3 hepatic veins (right, middle and left), these drain into the inferior vena cava

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17
Q

The right and left hepatic duct converge to form which duct?

A

The common hepatic duct

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18
Q

Where int deliver do the right and hepatic ducts converge?

A

The hilum

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19
Q

Which duct does the common hepatic duct converge with to form the common bile duct?

A

The cystic duct

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20
Q

What is the primary function for the common bile duct?

A

Carry bile to the duodenum of the small intestine. Bile produced by the liver is pushed back up the cystic duct y peristalsis to arrive in the gallbladder for storage.

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21
Q

What are the three main hepatic veins?

A

Right hepatic vein
Middle hepatic vein
Left hepatic vein

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22
Q

What is the middle hepatic vein, and its role in liver anatomy?

A

Obliquely runs from the inferior vena cava to the gallbladder fossa. Separates the anterior segment of the right hepatic lobe from the medial segment of the hepatic lobe

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23
Q

What is the right hepatic vein and its anatomical divisions?

A

Divides anterior and posterior segments of the right hepatic lobe

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24
Q

What is the left hepatic vein and its anatomical divisions?

A

Left hepatic vein separates the medial and lateral segments of the left hepatic lobe

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25
Q

Where do the 3 hepatic veins drain into?

A

Drain into the inferior vena cava

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26
Q

Which ligament separates the lateral and medial segments?

A

Ligamentum teres

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27
Q

Which lobe is associated with the medial segment?

A

Quadrate lobe

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28
Q

How segments comprise one liver?

A

8 segments

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29
Q

Each segment contains what?

A

Has its own vascular inflow, outflow and binary drainage

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30
Q

What is in the centre of each hepatic lobule?

A

Branch of the oral vein, hepatic artery & bile duct

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31
Q

What is the first hepatic segment?

A

Caudate lobe, situated posterior, recieves supply from both right and left branches of the portal, contains multiple hepatic veins

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32
Q

Which lobe is associated with the first hepatic segment?

A

Caudate lobe

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33
Q

Which branches of hepatic portal veins supply the first hepatic segment?

A

Right and left

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34
Q

In which direction are segments II - VII numbered?

A

Clockwise fashion

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35
Q

Which hepatic veins forms the drainage of segments (1-4)?

A

Middle and left hepatic vein

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36
Q

Which segments reside lateral to the falciform ligament?

A

Segments II & III

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37
Q

what is the relation of the portal venous supply to segment II & III?

A

Segment II is superior to the portal venous supply, and III is inferior.

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38
Q

Which segment is medial to the falciform ligament?

A

Segment IV

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39
Q

Which hepatic segment is the most inferior and medial

A

Segment V

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40
Q

Which vein forms the drainage of segments 5-8?

A

Right hepatic vein

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41
Q

Which hepatic segment is the most posterior?

A

Segment VI

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42
Q

Which segment is superior to segment VI?

A

Segment VII

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43
Q

Which hepatic segment is in the super medial position?

A

Segment VIII (8)

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44
Q

What are the three main components of the liver?

A

Hepatocytes
Bile canaliculi
Hepatic sinusoids

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45
Q

What are the main hepatic cells?

A

Hepatocytes

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46
Q

What term is used to describe plates of hepatocytes?

A

Hepatic laminae

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47
Q

What are hepatic laminae?

A

Hepatic laminae radiate outward from the portal vein in each hepatic lobule.

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48
Q

What is in the central of the hepatic lobule?

A

Central vein

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49
Q

What is the central vein in the hepatic lobule?

A

Collects blood from the hepatic sinusoids –> hepatic vein to the inferior venous cava

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50
Q

What are the two side faces of the lobule hepatocyte rows?

A

Sinusoid facing side, and bile canaliculi facing side

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51
Q

What is the function performed by bile canaliculi?

A

Adjacent hepatocytes, grooves in cell surface membrane provides bile canaliculus  Accumulate bile produced by hepatocytes. Bilirubin processed & excreted into bile canaliculi.

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52
Q

What is a hepatic sinusoid?

A

Open porous blood space formed by sinusoidal capillaries from hepatic portal veins
Hepatocytes are densely packed around sinusoidal epithelium, proving accessibility to blood supply
. From central position, hepatocytes process nutrients, toxins and waste substrate. Hepatic sinusoids combine, sending blood to a central vein  Hepatic vein  Inferior vena cava. (Blood & bile flow in opposite directions).

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53
Q

What is a portal triad?

A

Arrangement around perimeter of hepatic lobules, consists of: Bile duct, hepatic artery branch, and a hepatic portal vein.

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54
Q

How many hepatic lobules are linked by a portal triad?

A

3 hepatic lobules

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55
Q

Describe the movement of bile through the ducts:

A

Bile flows into bile ductules  Bile duct  Right & left hepatic ducts  Common hepatic duct + Cystic duct (from gallbladder)  Common bile duct.

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56
Q

What is the role of the hepatic artery?

A

Delivers oxygenated blood into the live to support the metabolic demands of hepatocytes

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57
Q

Where does the portal vein arise from?

A

Mixed venous blood from the gastrointestinal tract (nutrients, bacteria & toxins), and spleen (metabolic waste substrates).
Hepatocytes process nutrients, detoxify & excrete waste.

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58
Q

What is the main outflow of the hepatic lobule?

A

Bile produced from hepatocytes drains into bile canaliculi, these ducts coalesce with cholangiocyte-lined bile ducts present around lobule perimeter

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59
Q

What is a hepatic acinus?

A

Consists of 1/6th of hepatic lobule, comprises of two portal triads extending into the hepatic lobule towards the central vein

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60
Q

Where does the central vein reside in relation to the acinus?

A

Resides within the acinus apex.

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61
Q

How many zones comprise a hepatic acinus?

A

Three

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62
Q

Which hepatic acinus zone has the greatest oxygen concentration?

A

Zone 1

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63
Q

Which hepatic acinus zone has the lowest oxygen concentration, and lowest toxin risk?

A

Zone 3

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64
Q

Describe the structure of sinusoidal endothelium?

A

Absence of basement membrane
The endothelium is fenestrated (discontinuous), therefore increasing permeability to substrate, facilitating the movement of lipids and substrates to and from hepatocytes

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65
Q

What space resides between the sinusoidal endothelial supply and the hepatocyte?

A

Space of Disse

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66
Q

What is the Space of Disse?

A

The perisinusoidal space, where the blood plasma is contained
Microvilli of hepatocytes extend into this space, allowing proteins and plasma components from the sinusoids to be absorbed by hepatocytes

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67
Q

Which cells reside in the Space of Disse?

A

Hepatic stellate cells

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68
Q

Which cells are attached to the sinusoidal endothelium?

A

Kupffer cells

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69
Q

What are Kupffer cells?

A

Kupffer cells are attached to the sinusoidal endothelium exhibiting the capacity to undergo phagocytosis, agonistically functioning as sinusoidal macrophages  Eliminating & detoxifying substances arriving in liver from portal circulation.
Hemosiderin store  Available production of haemoglobin.

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70
Q

Which hepatic cells store vitamin A?

A

Stellate cells

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71
Q

What are hepatic stellate cells?

A

Hepatic stellate cells reside within the perisinusoidal space, the Space of Disse. Exist in quiescent state, providing available storage of Vitamin A in cytosolic droplets.
Stellate cells undergo activation in response to hepatic damage, expressing fibroblast activity  Proliferate, chemotactic & deposit collagen in extra-cellular matrix.

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72
Q

What are hepatocytes?

A

Cubical cells responsible for the synthesis of albumin, clotting factors & bile salts. Site of drug metabolism; receives nutrients & substrates from sinusoids.
80% of liver mass

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73
Q

Where do cholangiocytes reside?

A

On the edge of the bile duct, secrete bicarbonate and water in bile

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74
Q

What do cholangiocytes secrete?

A

Bicarbonate & water into bile

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75
Q

What are the main functions of hepatocytes?

A

Metabolic & catabolic functions: Synthesis & utilisation of carbohydrates, lipids and proteins.
Secretory & excretory function: Synthesis and secretion of proteins, bile & waste prodcuts
Detoxification & immunological functions: Degradation of ingested pathogens, and processing of drugs
Carbohydrate metabolism

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76
Q

What is glycolysis?

A

Glycolysis: Anaerobic conversion of glucose  Lactate (RBCs, renal medulla & skeletal muscle); aerobic oxidation of glucose  Pyruvate (CNS, heart, skeletal muscle).

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77
Q

What is glycogenesis?

A

Synthesis of glycogen from glucose (Liver & muscle)

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78
Q

What is glycogenolysis?

A

Breakdown of glycogen to glucose

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79
Q

What is gluconeogenesi?

A

Gluconeogenesis: Production of glucose from non-sugar substrates: Amino acids (glutamine) in liver & renal cortex; lactate (from anaerobic glycolysis in RBCs & muscles); glycerol from lipolysis.

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80
Q

What is lipolysis?

A

Hydrolysis of triacylglycerols into glycerol and free fatty acids

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81
Q

What is lipoegenesis?

A

Synthesis of triacylglycerols (storage in adipose tissue)

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82
Q

Which cycle converts lactate into pyruvate?

A

The Cori cycle

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83
Q

What is the Cori cycle?

A

Refers to the metabolic pathway in which lactate produced through anaerobic glycolysis in the myocyte is transported to the liver under The action of lactate dehydrogenase to form pyruvate
Converted into glucose via gluconeogenesis

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84
Q

Where do amino acids undergo protein synthesis?

A

Within the liver

85
Q

What proteins are formed within the liver?

A

Lipoproteins
Plasma proteins (albumin)
Clotting factors

86
Q

Which enzyme are involved in the conversion of amino acids?

A

Transaminases

87
Q

Alpha keto-glutarate can be converted into which 3 amino acids?

A

Glutamine
Proline
Arginine

88
Q

Pyruvate can be converted into which 3 amino acids?

A

Alanine, valine and leucine

89
Q

What amino acid is pyruvate transaminate into in the glucose-alanine cycle?

A

Alanine

90
Q

What type of amino acid is alanine?

A

Glucogenic amino acid

91
Q

How is pyruvate converted into alanine?

A

The amino group on glutamate is transferred to pyruvate by aminotransferase generating alpha-keto-glutarate, and converting pyruvate to alanine

92
Q

How is nitrogen transported to the liver?

A

Nitrogen is also transported to the liver in form of glutamine, synthesised from glutamate and ammonia in reaction catalysed by glutamine synthetase  Ammonia released through action of glutaminase.

93
Q

Which cells stored triglycerides?

A

Adipocytes

94
Q

Which enzymes hydrolyse triglycerides into fatty acids in adipose tissue?

A

Hormone sensitive lipase

95
Q

How are fatty acids shuttled into the liver?

A

Carnitine shuttle

96
Q

What is the fate of fatty acids in the liver?

A

Undergo beta oxidation, into acetyl CoA, enters into the TCA cycle or substrate for ketogenesi

97
Q

What is the main energy store within the liver?

A

Glycogen

98
Q

What happens when glycogen hepatic storage reaches maximum capacity?

A

Results in glucose and amino acid conversion into triglycerides as storage within liver and adipose tissue.

99
Q

2 molecules of acetyl-CoA form what compound?

A

Acetoacetate

100
Q

How are lipids, triacylglyerols and cholesterol transported?

A

Lipoproteins

101
Q

What are lipoproteins?

A

globular micelle like particles that consist of nonpolar core of triacylglycerols, and cholesteryl-esters surrounded by an amphiphilic coating of protein, phospholipid & cholesterol.

102
Q

Which molecules transports triacylglycerols and cholesterol from small intestines to tissues?

A

Chylomicrons

103
Q

Which lipoproteins transport endogenous triacylglycerols and cholesterol from the liver to tissues?

A

LDLs
IDLs
VLDls

104
Q

What are HDLs?

A

High density lipoproteins, transport endogenous cholesterol from tissues to the liver

105
Q

What is the lipoprotein synthesis pathway?

A

𝑮𝒍𝒖𝒄𝒐𝒔𝒆→𝑷𝒚𝒓𝒖𝒗𝒂𝒕𝒆 →𝑨𝒄𝒆𝒕𝒚𝒍−𝑪𝒐𝑨 →𝑭𝒂𝒕𝒕𝒚 𝒂𝒄𝒊𝒅𝒔 & 𝑪𝒉𝒐𝒍𝒆𝒔𝒕𝒆𝒓𝒐𝒍

𝑮𝒍𝒖𝒄𝒐𝒔𝒆 →𝑮𝒍𝒚𝒄𝒆𝒓𝒐𝒍

𝑮𝒍𝒖𝒄𝒐𝒔𝒆+𝟑 𝑭𝒂𝒕𝒕𝒚 𝒂𝒄𝒊𝒅𝒔 →𝑻𝒓𝒊𝒂𝒄𝒚𝒍𝒈𝒍𝒚𝒄𝒆𝒓𝒐𝒍+𝑨𝒑𝒐𝒑𝒓𝒐𝒕𝒆𝒊𝒏 𝒑𝒉𝒐𝒔𝒑𝒉𝒐𝒍𝒊𝒑𝒊𝒅𝒔+𝒄𝒉𝒐𝒍𝒆𝒔𝒕𝒆𝒓𝒐𝒍 →𝑪𝒉𝒚𝒍𝒐𝒎𝒊𝒄𝒓𝒐𝒏𝒔

106
Q

What are the three main functions of cholesterol?

A

Stabilisation and membrane integrity through fluid dynamics within the phospholipid bilayer
Steroidgenesis (mineralcorticoids, cortisol, and aldosterone)
Vitamin K synthesis (essential for clotting factors)

107
Q

Which clotting factors are reliant on vitamin K?

A

II, VII, IX, X

108
Q

Which fat soluble vitamins are stored by hepatocytes?

A

A, D, E, K

109
Q

Where is vitamin b12 stored?

A

Within hepatocytes

110
Q

Where is copper stored?

A

Within hepatocytes

111
Q

How long are the fat soluble vitamins stored for within hepatocytes?

A

6-12 months except Vitamin K

112
Q

How is iron stored within the liver?

A

As ferritin and hemosiderin

113
Q

Which disease result sin increased copper deposition?

A

Wilson’s disease

114
Q

What is haemochromatosis associated with?

A

Elevated iron levels

115
Q

Which enzymes are involved in detoxification?

A

P450 enzymes

116
Q

What is phase 1 of detoxification?

A

Modification, p450 enzymes are the predominant catalysts of phase 1 metabolism in liver. Phase 1 reactions are classified into: Oxidation, reduction & hydrolysis

117
Q

What is the purpose of phase 1 detoxification?

A

More hydrophilic xenobiotics

118
Q

What is oxidation in terms of xenobiotic metabolism?

A

Addition of oxygen into xenobiotic

119
Q

What is phase 2 of detoxification?

A

Conjugation

120
Q

What happens during the conjugation (Phase II) phase of detoxication?

A

Activated xenobiotic metabolites are conjugated with a charged polar species
Products of conjugation reactions have increased molecular weight, tend to be less active
The addition of large anionic groups detoxifies reactive electrophiles, and produces more polar metabolites that cannot diffuse across membranes, thus are active transported

121
Q

Where do right and left hepatic ducts converge?

A

At the hepatic hilum (portages hepatitis)

122
Q

The right and left hepatic duct converge together to form what?

A

The common hepatic duct

123
Q

Which duct converges with the common hepatic duct to form the common bile duct?

A

The cystic duct arising from the gall bladder

124
Q

Where does the common bile duct converge with the main pancreatic duct?

A

Ampulla of Vater

125
Q

Which spinchter regulates the entry of bile and pancreatic secretions into the duodenum?

A

The Sphincter of Oddi

126
Q

What forms the majority of bile?

A

Water 97%

127
Q

What colour is bilirubin?

A

Yellow-brownish pigment

128
Q

What colour is biliverdin?

A

Green

129
Q

Which cells secrete bile?

A

Cholangiocytes and hepatocytes

130
Q

What components and molecules are essential for the emulsification of lipids?

A

Bile salts & phospholipids

Exhibit hydrophobic and hydrophilic properties

131
Q

What is the function of the hydrophobic and hydrophilic regions of bile?

A

Interacts with large lipid molecules whereas the hydrophilic regions interacts with the watery chyme within the duodenum

132
Q

How are bile salts reclaimed?

A

Reclaimed by enterohepatic circulation, bile in ileum absorbed and returned to liver in the hepatic portal blood system

133
Q

What are the three main functions of bile?

A

Cholesterol homeostasis
Absorption of lipids & lipid soluble vitamins (A,D,E & K)
Excretion of: Xenobiotics, cholesterol metabolic, steroid hormones & alkaline phosphatases

134
Q

What % bile secretion is attributed to hepatocytes?

A

60%

135
Q

What function do cholangiocytes perform in secondary modification of bile?

A

Cholangiocytes lining the bile duct modify the canalicular bile, altering the pH (alkaline electrolyte solution), water is drawn into bile by osmosis via paracellular junctions. Canalicular bile enters the lumen of the canals of Hering, percolating towards the Cholangiocytes. These processes includes the active secretion of Cl- and HCO3- into the bile by CFTR proteins (Cystic fibrosis transmembrane regulatory).
Luminal glucose & organic acids reabsorbed
IgA exocytosis

136
Q

Which protein transporter secretes bicarbonate ions into the bile?

A

CFTR proteins

137
Q

What immunoglobulin is exocytosed by cholagiocytes?

A

IgA

138
Q

What is the main biliary transporter?

A

Bile salt excretory pump (BSEP): Active transport of bile acid into bile

139
Q

What is the function of MDR3?

A

Excretion of phosphatidylcholine

140
Q

What is the function of MDR1?

A

Excretion of xenobiotics and cytotoxins into the bile

141
Q

Which transporter located on the basolateral membrane transports bile salts & xenobiotics from the sinusoidal blood into the hepatocytes?

A

OATP transporters

142
Q

What are OATP transporters?

A

OATP transporters present on the basolateral membrane transport bile salt & xenobiotics from the sinusoidal blood (portal) into the hepatocyte.

143
Q

What are NTCP transporters?

A

Sodium dependent uptake transporters are expressed on the basolateral membrane
Uptake of bile salts from sinusoidal blood

144
Q

Which is the main precursor of bile salts?

A

Cholesterol

145
Q

Describe the pathway of cholic acid formation?

A

Cholesterol -> 7-alpha hydrocholesterol -> cholic acid

146
Q

What are the two primary bile salts?

A

Cholic acids

Chenodeoxycholic acid

147
Q

What is the pathway of chenodeoxycholic acid formation?

A

Alternative pathway: Cholesterol  27-hydroxycholesterol (CYP27A-1)  Chenodeoxycholic acid (CYP7B1).

148
Q

Where are the primary bile salts synthesised?

A

Within hepatocytes & cholangiocytes

149
Q

Where are the primary salts secreted into?

A

Through the common bile duct into the duodenum via the ampulla of Vater

150
Q

Which ion salts are conjugated in the liver to glycine & taurine?

A

Sodium and potassium ion salts

151
Q

What are the two main secondary bile salts?

A

Deoxycholic acid

Lithocholic acid

152
Q

Where does primary bile salt biotransformation occur?

A

Occurs within the duodenum and jejunum by intestinal bacteria

153
Q

What is the function of bile salts in terms of fats?

A

Reduces surface tension of fats - emulsification of lipids prior to digestion an absorption

154
Q

What do bile salts form?

A 
Bile salts form micelles *(steroid nucleus planar), exhibits amphiphatic characteristics 
Hydrophilic domains (carboxyl and hydroxyl groups) are externally exposed forming hydrogen bonds with water, and subsequently dissolving 
Hydrophobic domain *nucleus and metal components
155
Q

What is encapsulated within the micelles?

A

FFAs and cholesterol, dissolve in lipids

156
Q

what is the mechanism of fat globule lipid absorption?

A

Fat globules within the duodenum & jejunum are emulsified by bile salts & phospholipids  Increases available surface area & binding sites for lipases (in conjunction with colipase) to hydrolyse the lipids into fatty acids & glycerol.

157
Q

Which enzyme assists lipase in the hydrolysis of lipids?

A

Colipase

158
Q

Which substrates stimulate CCK release?

A

Peptids and fatty acids

159
Q

Which cells release CCK?

A

Enteroendocrine I mucous cells within the duodenal during the intestinal phase

160
Q

When is CCK released during the gastric phases?

A

Intestinal phase formulating the enteric inhibitory phase

161
Q

What effect does CCK have on the gall bladder?

A

Stimulates gall bladder contraction, facilitating the movement of bile through the common bile duct into the duodenum via the ampulla of Water, this action is potentiated by the relaxation of the Sphincter of Oddi

162
Q

Which sphincter relaxes in response to CCK stimulation?

A

Sphincter of Oddi

163
Q

Which receptor is activated by CCK action?

A

CCKI receptor

164
Q

What state is the Sphincter of Oddi in, pre-prandially?

A

Constricted- coxed state, bile is diverted upwards through the cystic duct into the gall bladder for storage

165
Q

Where is 95% of bile salts absorbed?

A

Absorbed from the terminal ileum through the Na+/Bile salt co-transport Na+/K+ ATPase system

166
Q

Which transporters causes enterocyte absorption of bile salts?

A

ABST

167
Q

Which channels do bile salts enter through into portal venous circulation?

A

OST channels

168
Q

Which transporters are used for bile salt uptake?

A

OATP-1 transporters on the basolateral membrane to resyntheise into bile

169
Q

What is the fate of 5% of bile salts within the ileum?

A

Dehydroxylated undergoing modification into secondary vile salts within the colon

170
Q

Which secondary bile salt is absorbed?

A

Deoxycholic acid

171
Q

Which secondary bile salt is excreted into the stool?

A

Lithocholic acid is excreted in the stool

172
Q

Where does the gallbladder reside?

A

Resides within the posterior aspect of the right lobe of the liver

173
Q

What are the three main regions of the gall bladder?

A

Fundus
Neck
Cystic duct

174
Q

What cell types form the gallbladder?

A

Simple columnar epithelium of the gallbladder mucosa is organised in rugae
There is no subbmucosa within the gall bladder wall

175
Q

Which layer do the smooth muscle fibres reside within?

A

Muscular layer

176
Q

Which receptors does CCK bind onto to cause gall bladder wall contraction?

A

CCKa receptors and neural plexus

177
Q

What is the main role performed by the mucosa wall of the gallbladder?

A

Mucosa absorbs water and ions from the bile, concentrates and acidifies the bile 10 -fold

178
Q

Where is 75% if bilirubin formed from?

A

Erythrocytes

179
Q

How are erythrocytes converted into unconjugated bilirubin?

A

Removed from circulation within the spleen, under the activity of haem oxygenase, the haem group is cleaved oxidatively to form biliverdin - central methanyl bridge is reduced into bilirubin

180
Q

What are the 3 main sources of bilirubin?

A

RBCs 75%
Catabolism of alternative haemoproteins (cytochromes) 22%
3% from ineffective bone marrow erythropoiesis>

181
Q

How is bilirubin transported within the blood?

A

Albumin plasma protein

182
Q

Which cells absorb bilirubin?

A

Hepatocyte

183
Q

Which molecules does bilirubin conjugate with within hepatocytes?

A

2 molecules of UDP-Glucuronic acid under the action of glucronyl-transferase –> Bilirubin diglucuronide (Direct BR)

184
Q

What is the name of conjugated bilirubin?

A

Bilirubin diglucuronide (Direct BR)

185
Q

Which transporter actively transported direct BR into the biliary canaliculi?

A

cMOAT transporter

186
Q

Which bilirubin is water insoluble?

A

Unconjugated bilirubin

187
Q

What % of bilirubin is excreted into faeces?

A

85%

188
Q

What is the fate of bilirubin in the faeces?

A

Bacterial enzymes in the large intestine hydrolyse the glucuronic acid groups in a multistep process  Urobilinogen (colourless & odourless)  Stercobilinogen  Stercobilin (Brown pigment)

189
Q

Which compound is responsible for the brown pigment in faecal matter?

A

Stercobilin

190
Q

Why does obstructive jaundice result in white stools?

A

No bile into large bowel therefore no bilirubin to be converted into stercobilin (White stools)

191
Q

What % of bilirubin enter into enterohepatic circulation?

A

14% enters enterohepatic circulation: BR  Deconjugated into lipophilic form (Urobilinogen & Stercobilinogen).

192
Q

What molecules arising from bilirubin is excreted by the kidneys?

A

Urobilin

193
Q

What are the 3 types of jaundice?

A

Prehepatic
Intrahepatic
Post-hepatic

194
Q

What is jaundice?

A

Characterised by elevated unconjugated serum bilirubin levels -> Yellowish pigmentation

195
Q

What are the main causes of prehepatic jaundice?

A

Bilirubin production is exaggerated due to erythrocyte abnormalities and degradation within the spleen, this potentiates the haem oxygenase activity in cleaving the haem groups to resultantly form unconjugated bilirubin. Conditions which are associated with this include: Sickle cell anaemia & hereditary spherocytosis

196
Q

What are the main causes of intrahepatic jaundice?

A

Intrahepatic jaundice is affiliated with dysfunctional hepatocytes. This includes:
Dysfunctional transporter proteins to intake indirect serum bilirubin from albumin
Decreased conjugation ability (Glucuronyl transferase inactivation)
Decreased outflow of conjugated bilirubin from hepatocytes (cMOAT inactivation or obstruction within biliary tree (canaliculi).

197
Q

What are the main causes of post-hepatic jaundice?

A

Interruption to the drainage of bile containing conjugated bilirubin in the biliary system. Associated causations include gallstones in the common bile duct, and pancreatic cancer in the head of the pancreas.

198
Q

What are gall stones?

A

Gall stones are crystalline masses formed abnormally within the gal bladder of bile ducts from bilirubin, cholesterol and calcium salts

199
Q

What is cholecystitis?

A

Inflammation of the gall bladder

200
Q

What is cholelithiasis?

A

The formation of gall stones resulting in obstruction within the bile ducts. Gallstone obstruction within the cystic duct causes Mirizzi’s syndrome.

201
Q

What is Mirizzi’s syndrome?

A

Gallstone obstruction within the cystic duct

202
Q

What are the common obstruction sites for gal stones?

A

Cystic duct
Common bile duct
Hepatopancreatic duct
Main pancreatic duct

203
Q

What is cholangitis?

A

Bacterial infection associated with the common bile duct

204
Q

What does ERCP mean?

A

Endoscopic retrograde cholangiopancreatography

205
Q

What is ERCP?

A

A procedure used to diagnose diseases of the gallbladder, biliary system, pancreas & liver. The procedure identifies upstream through the main pancreatic duct, common bile duct towards the biliary system in comparison to entrance through the Ampulla of Vater within the duodenum.
Wires can be inserted into the common bile duct to assist with the removal of obstructive bile stones within the common bile ducts, this can be identified using contrast dyes (cholangiogram) (Obstruction = black).

206
Q

What is spincterotomy?

A

Small incision of the sphincter of Oddi within the Ampulla of Vater, can help remove small gallstones

207
Q

How can a stent placement relieve gall stones?

A

Stent is a drainage tube that misplaced in the bile duct or the pancreatic duct to hold the duct open allowing it to drain

208
Q

What is the main limitation of gallstone removal using ERCP?

A

ERCP remove gall stones from bile duct not gallbladder itself.

209
Q

What does PTC mean?

A

Percutaneous Transhepatic Cholangiography

BRS (Bioregulatory Systems) (38 decks)

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