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Phase 1 flashcards > Liver > Flashcards

Liver Flashcards

1
Q

name the three types of proteins made by the liver

A

albumin
most clotting factors
complement proteins - mark pathogens in the immune response

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2
Q

function of albumin

A

carry unconjugated bilirubin
plasma protein

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3
Q

are proteins stored as they are?

A

no, always have a function
if no function, used for energy or stored as fat

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4
Q

how are faulty proteins degraded?

A

ubiquitin
- in cell cytoplasm
- small protein ubiquitin selectively binds to defective protein
signals to proteases that protein needs breakdown

lysosomal
- reticuloendothelial system (liver)
- sinusoid endothelial cells remove protein from blood
- protein fused into lysosomes
- phagocytosed by Kuppfer cells

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5
Q

name functions of the liver

A

storage
- vitamins
- fats
- carbohydrates
- minerals such as iron and copper

synthetic
- produces proteins such as clotting factors, plasma proteins and complement proteins

immune
- resident macrophages: Kuppfer cells

hormonal regulation
- oestrogen

digestion
- produces bile

metabolism
- carbohydrate
- fat
- protein
- hormone

toxin/ drug metabolism and excretion

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6
Q

which clotting factor is not produced by the liver?

A

Von Willebrand - produced by endothelial cells

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7
Q

what is the reticuloendothelial system?

A

resident macrophages residing in tissues systemically
e.g liver Kuppfer cells and alveolar macrophages

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8
Q

in which quadrant is the liver found?

A

right upper quadrant

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9
Q

why is the liver important with regards to vitamin K?

A

bile salts produced in the liver are necessary to absorb vitamin K
vitamin K is required to produce clotting factors 10, 9, 7, 2

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10
Q

fate of amino acids

A

catabolised for energy breakdown - enters Krebs
excreted as urea

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11
Q

when metabolising amino acids for energy, which is the key intermediate we always start with?

A

alpha ketoglutarate

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12
Q

mechanism of amino acid catabolism

A

transamination then oxidative deamination

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13
Q

describe transamination
include the fate of the products

A

alpha ketoglutarate accepts amine from alanine
forms glutamate and pyruvate
catalysed by alanine transferase
alphaketoglutarate + alanine —> glutamate + pyruvate

pyruvate for
- gluconeogenesis
- aerobic respiration

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14
Q

describe oxidative deamination

A

glutamate hydrolysed to reform alphaketoglutarate and ammonia
catalysed by glutamate dehydrogenase
glutamate + water –> alpha ketoglutarate + ammonia

toxic ammonia is removed to enter urea cycle

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15
Q

what is a negative nitrogen balance?

A

catabolism
more nitrogen out than in

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16
Q

what is a positive nitrogen balance?

A

anabolism
more nitrogen in than out

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17
Q

what determines nitrogen balance?

A

protein intake
loss or gain of total body protein

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18
Q

draw the urea cycle

A

.

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19
Q

major amino acids in the urea cycle

A

arginine, ornithine, citrulline
‘CITARGORN’

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20
Q

why is ammonia harmful?

A

neurotoxic, can cross blood brain barrier

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21
Q

what is the glucose alanine cycle?

A

involves muscle protein being degraded to provide more glucose to generate additional ATP for muscle contraction

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22
Q

describe the glucose alanine cycle

A
  1. reverse transamination in muscles
    glutamate + pyruvate –> alanine + alphaketoglutarate
  2. alanine to liver (in blood)
  3. transamination in liver
    alanine + alphaketoglutarate —> glutamate + pyruvate
    glutamate is oxidatively deaminated to remove excess ammonia in the urea cycle
    pyruvate is converted to glucose in the liver (gluconeogenesis)
  4. glucose back to muscle cells
  5. glycolysis (to pyruvate)
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23
Q

which are the fat soluble vitamins?

A

A,D,E,K

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24
Q

functions of lipids

A

energy reserve - fatty acid beta oxidation
shock absorber
cell membrane components - phospholipids and cholesterol
hormones, metabolism

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25
Q

energy content of lipids

A

9kcal/g

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26
Q

structure of lipoproteins

A

outer glycoprotein, inner lipid

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27
Q

what is ‘good’ cholesterol and why?

A

HDLs - high density lipoproteins
highest protein to lipid ratio

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28
Q

where are HDLs synthesised?

A

liver

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29
Q

function of HDLs

A

remove cholesterol from cells to take to the liver

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30
Q

where are LDLs produced?

A

plasma

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31
Q

function of LDLs

A

deposit cholesterol in cells

32
Q

what are VLDLs

A

very low density lipoproteins
carry triglycerides to adipose tissue

33
Q

what are IDLs?

A

VLDL intermediates
converted to LDL

34
Q

when does beta oxidation of fatty acids occur?

A

in the fasted state
high glucagon and low insulin

35
Q

name types of beta oxidation of fatty acids

A

peroxisomal
mitochondrial - main

36
Q

what is a xenobiotic?

A

foreign substance to be excreted
modified by the liver to be less lipophilic and more hydrophilic to increase solubility
e.g drugs

37
Q

what are the phase 1 biotransformation reactions?

A

addition/ exposure of a functional group
most commonly produces a hydroxyl group
small increase in hydrophilicity
oxidation, reduction or hydrolysis
microsomal enzymes in endoplasmic reticulum - CYP450 enzymes

38
Q

what are phase 2 conjugation reactions?

A

conjugation to produce hydrophilic metabolites
large increase in hydrophilicity
glucoronidation - most common
examples of conjugation molecules
- glucaronic acid
- sulphate
non microsomal enzymes - enzyme UGT

39
Q

alcohol detoxification - a different type

A

metabolism of alcohol does not fit into type 1 or 2 detoxification
does not need to be conjugated for excretion

alcohol –> acetaldehyde –> acetate –> carbon dioxide and water

enzymes for the first two steps: alcohol dehydrogenase, acetaldehyde dehydrogenase

40
Q

does alcohol need to be conjugated for excretion?

A

no

41
Q

constituents of bile

A

bile salts
cholesterol
xenobiotics
electrolytes
phospholipids
bilirubin

42
Q

what is the portal triad?

A

hepatic portal vein, hepatic artery, bile duct

43
Q

where are portal triads found?

A

vertexes of hepatic lobules

44
Q

histological appearance of liver tissue

A

hexagonal lobules
lobules have a central hepatic vein (not hepatic portal vein)
in the corners of the lobules we find the portal triad

45
Q

what is the hepatoduodenal ligament and what does it contain?

A

part of the lesser omentum
connects the porta hepatis of the liver to the duodenum
contains
- portal vein
- hepatic artery (right and left)
- common hepatic duct

46
Q

what percentage of bile is excreted?

A

about 5

47
Q

where is bile reabsorbed? what percentage?

A

ileum
95%

48
Q

function of CCK

A

relaxes the sphincter of Oddi
gallbladder contraction

chole, “bile”; cysto, “sac”; kinin, “move”

49
Q

how is bile reabsorbed?

A

into portal blood
using apical Na+ bile acid transporter (ASBT)

50
Q

function of iron in body

A

muscle myoglobin
erythrocytes

51
Q

what is directly proportional to the total iron stores in the body?

A

ferritin levels

52
Q

what causes low ferritin?

A

iron deficiency

53
Q

what amount of ferritin suggest depletion?
and absence of stored iron

A

less than 20ug/L
12ug/L

54
Q

functions of vitamins

A

gene activators
free radical scavengers
coenzymes or cofactors in metabolic reactions

55
Q

vitamin a sources

A

retinol
carotenoids

56
Q

functions of vitamin a

A

vision
- used to form rhopsodin in the rod cells in the retina
spermatogenesis
prevention of foetal resorption

57
Q

vitamin a excess

A

joint and bone pain
reversible yellowing of the skin
abdominal pain

58
Q

function of vitamin d

A

calcium absorption

59
Q

vitamin d deficiency

A

demineralisation of bone
- rickets in children
- osteomalacia in adults

60
Q

function of vitamin e

A

antioxidant

61
Q

vitamin e requirements

A

4mg/ day in men
3mg/ day

62
Q

causes of vitamin e deficiency

A

fat malabsorption

63
Q

which vitamins does the liver store?

A

ADEK fat soluble

64
Q

which clotting factors are vitamin K dependent?

A

2, 7, 9, 10
1972

65
Q

deficiency of what substance causes neural tube defects?

A

folate

66
Q

which clotting factors are produced by the liver?

A

1, 2, 4, 5, 6, 7

67
Q

functions of fat

A

energy reserve
hormone metabolism
part of cell membranes
inflammatory cascades
steroid hormones - cholesterol

68
Q

where is cholesterol made?

A

liver

69
Q

what percentage of cholesterol is endogenous?

A

90%

70
Q

what percentage of cholesterol is dietary?

A

10%

71
Q

what is the only way cholesterol is exported?

A

through bile excretion

72
Q

what is enterohepatic circulation?

A

movement of bile acid molecules from the liver to the small intestine and back to the liver

73
Q

how are triglycerides and cholesterol carried through the circulatory system?

A

lipoproteins

74
Q

energy content of lipids

A

9kcal/g

75
Q

what carries lipids from the gut to muscle and adipose tissue?

A

chylomicrons

76
Q

order
HDL
VLDL
LDL
chylomicron
in order of highest to lowest lipid to protein ratio

A

highest lipid to protein ratio means more lipid compared to protein
chylomicron
VLDL
LDL
HDL

77
Q

what happens to chylomicron remnants?

A

taken up by liver by receptor mediated endocytosis - recognition of ApoB by hepatocyte surface receptors

Phase 1 flashcards (27 decks)

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