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Body Systems > Structure and function of the liver > Flashcards

Structure and function of the liver Flashcards

1
Q

where is the liver and what is its structure

A

lies on RHS of upper abdomen and protected by lower ribs
has two lobes
covered in capsule of connective tissue

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2
Q

what is the function of the common bile duct

A

transports bile synthesised in the liver to the duodenum

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3
Q

what does the common bile duct merge with

A

the pancreatic duct to form a common passageway known as the ampulla of vater

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4
Q

what regulates secretions into the duodenum

A

sphincter of oddi

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5
Q

what happens to the all bladder during meals

A

stimulated to contract and forcing stored bile down the common bile duct

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6
Q

how much blood supply does the liver receive from the heart

A

25% of resting cardiac output

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7
Q

what are the two main inputs of blood supply to the liver and where does it stem from

A 
portal vein (75%) - from small intestine, stomach, pancreas, spleen 
hepatic artery (25%) - oxygenated blood
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8
Q

what is the output of blood from the liver

A

hepatic vein - into inferior vena cava

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9
Q

describe the structure of the lobules in the liver

A

hexagonal with a portal tract at each angle - contains 3 vessels (HPV, HA, bile duct)
blood from the hepatic artery and HPV flow in sinusoids

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10
Q

what is the flow of bile in the liver

A

from the cells in the liver down bile cannliculi to the bile ducts ie in the opposite direction to the blood flow

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11
Q

where is the space of disse

A

between the hepatocytes and the endothelial cells

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12
Q

what fills the space of disse

A

stellate cells and collagen fibres

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13
Q

what are the 5 types of cells in the liver

A

hepatocytes
endothelial cells
kupffer cells
pit cells (liver associated lymphocytes)
hepatic stellate cells (Ito cells or lipocytes)

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14
Q

what are the most common cells in the liver

A

hepatocytes (60%)

carry out most metabolic functions

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15
Q

what is the structure of endothelial cells in the liver

A

lining cells of the sinusoids

contain fenestrations so do not form a barrier against small molecules

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16
Q

what are kupffer cells

A

located within sinusoidal lining - macrophages

phagocytose bacteria, old erythrocytes, protect liver from gut derived bacteria

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17
Q

what are pit cells in the liver (liver associated lymphocytes)

A

NK cells - help protect against tumours or viruses

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18
Q

what are and what is the role of hepatic stellate cells (Ito cells or lipocytes)

A

lipid filled cells
primary site of vit A storage
control turnover of connective tissue, synthesise collagen and regulate contractility of sinusoids

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19
Q

what are the two main functions of the liver

A

“the factory” - raw materials, making new stuff, recycling, storage
carb, lipid and protein metabolism, bile formation

waste management
detoxification of xenobiotics
removal of waste such as degradation of bilirubin

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20
Q

what 8 modules can be stored in the liver

A

glucose as glycogen

vit A,D,K, B12, iron, copper

21
Q

what are the 3 metabolic functions of the liver

A

raining blood glucose levels
nitrogen metabolism
lipid metabolism

22
Q

what blood components are synthesised in the liver

A

albumin, clotting factors, lipoproteins

23
Q

what is bile made from

A

made up of water, bicarbonate, bile salts, cholesterol, phospholipids

24
Q

describe the formation of bile

A

formed in the hepatocytes from cholesterol. hydroxylation and then conjugation with glycine or taurine

25
Q

describe the recirculation of bile

A

reabsorbed into the portal vein from the intestine

26
Q

describe how cholestryamine lowers blood cholesterol

A

binds to bile acids in the gut and prevents recirculation and therefore more cholesterol used to form bile acids

27
Q

what are gall stones

A

more cholesterol enters the bile than can be solubilised by bile slats which causes precipitation - these stones get stuck in the common bile duct

28
Q

what diseases are caused by gall stones

A

biliary colic and acute cholecystitis

29
Q

what are xenobiotics and give examples

A

toxic or of no nutritional value
drugs - both pharma and recreational
food additives or toxins in food

30
Q

what waste products are broken down by the liver

A

hormones eg insulin, GH and oestrogen
bilirubin - breakdown of erythrocytes
urea - removal of NH4 ions mainly from metabolism of protein

31
Q

describe of a xenobiotic compound becomes a secondary metabolite

A

phase one reactions (hydroxylation, hydrolysis, redox) - primary metabolite
phase two reactions (conjugation, sulphonation, glucuronidation) - secondary metabolite

32
Q

what is the difference between phase 1 and phase two products

A

phase 1 - catabolic and often yield more reactive substances
phase 2 - produce inactive compounds with decreased lipid solubility to aid excretion

33
Q

what dictates phase 1 metabolism

A

CYP P450 enzymes

34
Q

where are CYP enzymes found

A

smooth ER

35
Q

can drugs affect CYP enzymes

A

enzymes are inducible baby drugs such as alcohol and carbamazepine

36
Q

what is phase 1 reactions catalysed by

A

molecular oxygen as donor of O atom, and requires NADPH as cofactor

37
Q

what in summary are phase two reactions

A

range of addition reactions mainly in the liver but also in other tissues such as lungs and kidneys

38
Q

what is a prodrug

A

inactive compound which is metabolised to produce the therapeutically active form in the body

39
Q

why do you use prodrugs

A

improve absorption of the drug in the gut

allow alternative routes of administration

40
Q

why are some women less affected by tamoxifen

A

they lack CYP2D6 depending on ethnic group and therefore less potent metabolite produced

41
Q

describe why taking too much paracetamol is bad

A

normally a phase two 2 pathway
when you take too much there is too little glutathione which allows free NAPQI to react with cell membranes
hepatic necrosis results and leads to liver failure

42
Q

describe the stages of bilirubin metabolism

A

first phase mainly by kupffer cells - haem broken down after 120 days to biliverdin which is greenish, then to bilirubin which is yellow/orange

43
Q

what is bilirubin attached to during transportation

A

albumin to liver hepatocytes

44
Q

what happens to bilirubin the the liver

A

conjugation (mainly glucuronic) and secretion into biliary canlicula (requires ATP)

45
Q

what happens to bilirubin in the gut

A

further metabolism by bacteria in the gut to urobilinogen which is then converted to urobilin (excreted in the urine) and stercobilin (excreted in faeces)

46
Q

what is preheaptic jaundice

A

too much haem maybe from haemolytic anaemia such as in sickle cell and liver can’t conjugate it all

47
Q

what is gilberts syndrome

A

harmless inherited disorder but not enough conjugating enzyme present - mild jaundice from illness

48
Q

what problems occur if problems with secretion of bile

A

gall stones - raised levels of conjugated bilirubin as leaks back into blood

Body Systems (77 decks)

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