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Nutrition and Digestion > Functional Microanatomy of the Liver > Flashcards

Functional Microanatomy of the Liver Flashcards

1
Q

what provides gross support to the liver

A

the collagen of the branching vascular system

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2
Q

what supports parenchymal cells of the liver

A

fine reticular fibres

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3
Q

what does the portal vein carry

A

food rich blood from the gut

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4
Q

what supplies arterial blood to the liver

A

hepatic artery

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5
Q

function of hepatic veins

A

takes away processed blood into the vena cava

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6
Q

what percentage of the blood supply comes from the hepatic artery vs. portal vein

A

hepatic artery - 25%
portal vein - 75%

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7
Q

what is the nerve supply to the liver

A

sympathetic and parasympathetic nerves supply perivascular structures but there is very little nerve supply at the sinusoidal level

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8
Q

what direction and speed does blood flow through the liver lobule

A

from portal triad to central vein
moves slowly to allow exchange of oxygen and nutrients

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9
Q

width of central vein wall

A

very thin

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10
Q

where are sublobular veins found

A

alone at periphery of the lobule

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11
Q

what is found in the portal area

A

portal triad

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12
Q

describe blood flow in hepatic lobules

A
  1. starts from branches of the portal vein and hepatic artery
  2. flows towards central vein via sinusoids
  3. blood collected in central veins goes to sublobular veins
  4. then to collecting veins
  5. then hepatic veins which leave the liver
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13
Q

describe bile flow in the liver

A

moves from centre to the peripheral bile ducts within a cell plate in a bile canaliculi

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14
Q

what are the three zones of the acinus

A
  1. periportal
  2. intermediate
  3. perivenous
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15
Q

what are the functions of the periporatl, intermediate and perivenous regions of the liver acinus

A

periportal - deals with sampling of the blood
intermediate - changes blood composition
perivenous - enriches blood

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16
Q

are liver sinusoids low or high pressure channesl

A

low - so blood moves slowly and has time to be processed

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17
Q

what cell type lines the liver sinusoids

A

fenestrated endothelial cells

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18
Q

are fenestrated endothelial cells that line the liver loosely or tightly attached and what do they rest upon

A

loosely
microvilli of underlying hepatic cells

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19
Q

what is the function of kupffer cells

A

policemen - surveillence

look for intruders
phagocytose them
send signals to other cells for help

20
Q

what is the space of diss

A

the space between the fenestrated epithlelial cells and the hepatocytes

21
Q

does the space of diss have a basal lamina

A

no but does contain extracellular matric materials

22
Q

what do stellate cells store

A

fat and vitamin A

23
Q

how do stellate cells respond to insults

A

make collagen and cause cirrhosis

24
Q

can RBCs enter the space of diss

A

no

25
Q

what function does the sinusoidal wall have in the embryo

A

haematopoiesis

26
Q

functions of sinusoidal wall

A

blood cleansing (e.g. of gut bacterial toxins)
bringing plasma in close contact with hepatocytes for its many functions

27
Q

at are the functions of the hepatocytes

A

storage
transformations
synthesis
regulation of plasma concentrations
detoxification
production of bile
production of acute-phase proteins which assist defence

28
Q

where is bile produced

A

hepatocytes

29
Q

where are bile canaliculi found

A

between neighboring hepatocytes

30
Q

which face of hepatocytes has microvilli in abundance

A

sinusoidal face
lateral faces which make the bile canaliculi don’t have many

31
Q

what shape are hepatocyte nuclei and how many nucleoli are there

A

round
one or two

32
Q

how many nuclei do hepatocytes have

A

mostly one but sometimes two

33
Q

what is the cause of portal hypertension

A

stellate cells depositing collagen which makes it harder for blood to pass through fenestrated epithelial cells so pressure is increased to overcome this

34
Q

how is lymph formed in the liver

A

by filtration of plasma into the spaces of disse

35
Q

what route do lymphatics follow

A

same as portal vein

36
Q

function of insulin

A

responds to high blood glucose
increases glycogen storage in liver
decreases gluconeogenesis
decreases glycogenolysis
increases glucose uptake
which decreases blood glucose

glucagon is the opposite

37
Q

describe bilirubin metabolism

A
  1. haemolysis in blood vessels forms unconjugated bilirubin
  2. unconjugated bilirubin turned into conjugated bilirubin in the liver
  3. conjugated bilirubin passed through biliary system into small intestine
  4. bacterial proteases in small intestine turn conjugated bilirubin into urobilinogen
    5a. 90% urobilinogen excrete in faeces
    5b. 10% urobilinogen returned to liver by the portal vein
  5. 10% urobilinogen returns to blood
  6. kidneys excrete 10% urobilinogen in urine
38
Q

what percentage of urobilinogen is excreted in stool vs. urine

A

90% stool
10% urine

39
Q

how does the liver carry out detoxification

A

takes fat soluble toxins and undergoes several steps to make them water soluble waste products which can be eliminated by the body in stool or urine

40
Q

what does a bilirubin LFT assess

A

transport from hepatocytes to biliary system

41
Q

what do aminotransferases LFTs assess

A

hepatocyte damage

42
Q

GGTs alone assess

A

drugs (e.g. antiepileptics)

43
Q

cholestasis can be assessed by what LFTs

A

GGT and alkaline phosphatase

44
Q

what LFTs test the protein synthesis/synthetic function of the liver

A

albumin
prothrombin time

45
Q

potential causes of jaundice

A

blockages of bile ducts due to
- gallstones
- tumours of head of the pancreas
- ampullary lesions

Nutrition and Digestion (30 decks)

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