hepatobiliary system Flashcards

1
Q

what does each portal triad contain

A

branch of hepatic artery
branch of portal vein
bile duct

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2
Q

what does the branch of hepatic artery do

A

brings O2 rich blood into the liver to support hepatocytes increased energy demands

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3
Q

what does the branch of portal vein do

A

mixed venous blood from GIT (nutrients, bacteria and toxins) and spleen (waste products)

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4
Q

what does the bile duct do

A

bile produced by hepatocytes drains into bile canaliculi

coalesce with cholangiocyte lined bile ducts around lobule perimeter

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5
Q

what is the blood supply of the liver (inflow)

A

dual blood supply
25% hepatic artery
75% portal vein

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6
Q

what is the blood supply of the liver (outflow)

A

bile

3 x hepatic veins (right, middle and left)

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7
Q

what sits in the inferior tissue of the liver

A

ligament teres

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8
Q

what is the 3 zone model

A

blood goes into the hepatic acinus via portal triad (point A)
blood drains out of hepatic acinus via central vein (point B)
hepatocytes near outer hepatic lobule (zone 1) receive early exposure to blood contents :
good components (O2)
bad components - toxins
acinus is split into 3 regions
zone 1 - high O2 and high toxin risk
zone 2 - medium O2 and medium toxin risk
zone 3 - low O2 and low toxin risk
exposure to toxins > hepatocytes in zone 1 die
if the liver becomes ischaemic > hepatocytes in zone 3 die

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9
Q

what are the liver cell types (5)

A
sinusoidal endothelial cells
kupffer cells
hepatic stellate cells
hepatocytes
cholangiocytes
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10
Q

what are sinusoidal endothelial cells

A

no basement membrane
fenestrated (discontinuous endothelium)
allows lipids and large molecule movement to and from hepatocytes

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11
Q

what are kupffer cells

A

sinusoidal macrophage cells
attached to endothelial cells ^
plays role in phagocytosis
eliminate and detoxify substances arriving in the liver from portal circulation

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12
Q

what are hepatic stellate cells

A

ito, perisinusoidal
exist in dormant state
stores vit A in liver cytosolic droplets
activated (fibroblasts) in response to liver damage
proliferate, chemotactic and deposit collagen in ECM

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13
Q

what are hepatocytes

A

80% of liver mass
cubical
synthesis eg. albumin, clotting factors and bile salts
drug metabolism
receive nutrients and building blocks from sinusoids to synthesise and metabolise
metabolic functions

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14
Q

what are cholangiocytes

A
secretes bicarbonate (HCO3-) and H2O into bile
line the biliary ducts
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15
Q

what are the 3 hepatocyte functions

A

1) metabolic and catabolic functions
synthesis and utilisation of carbohydrates, lipids and proteins
2) secretory and excretory functions
synthesis and secretions of proteins, bile and waste products
3) detoxification and immunological functions
breakdown of ingested pathogens and processing drugs

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16
Q

what is glycolysis

A

anaerobic conversion of glucose to lactate (RBCs, renal medulla and skeletal muscle)
aerobic oxidation of glucose (CNS, heart, skeletal muscle and most organs)

17
Q

what is glycogenesis

A

synthesis of glycogen from glucose (liver and muscle)

18
Q

what is glycogenolysis

A

breakdown of glycogen to glucose

19
Q

what is gluconeogenesis

A

production of glucose from non sugar molecules
amino acids (glutamine) in liver and renal cortex
lactate (from anaerobic glycolysis in RBCs and muscles)
glycerol (from lipolysis)

20
Q

what is lipolysis

A

breakdown of triacylglycerols to glycerol and FFAs

21
Q

what is lipogenesis

A

synthesis of triacylglycerols (storage in fat depots)

22
Q

where does the cori cycle happen

A

muscle cells

23
Q

STEPS for carbohydrate metabolism - Cori cycle

A

1) lactate produced by aerobic glycolysis of the muscle moves to the liver then the
glucose returns to muscle
2) muscles use O2 and glucose to make ATP (energy)
the availability of O2 for ETP becomes limited/decreases
3) the TCA cycle = inhibited > build up of pyruvate/pyruvic acid
glycolysis can still occur as no O2 is needed
4) more pyruvate is made by glycolysis > fermentation > lactate
liver
5) lactate is shuttled to liver where using lactate dehydrogenase becomes pyruvate
6) pyruvate undergoes gluconeogenesis and 6 ATP becomes glucose which can be
shuttled to muscle cells for use