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Year 2 Heme lymph > Hb synthesis and catabolism, choudhury > Flashcards

Hb synthesis and catabolism, choudhury Flashcards

1
Q

structure of heme

A

porphyrin ring structure with one Fe atom chelated in center by 4 N atoms
reversible O2 attachement

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2
Q

1 Hb can carry how much O2

A

4 molecules

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3
Q

how does nonheme get absorbed

A

as Fe2+ so through DMT1 driven by H+ gradient

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4
Q

how is Fe2+ transported to basolateral membrane

A

mobilferrin

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5
Q

how is heme iron absorbed

A

duodenal epithelial cells via binding or endocytoses

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6
Q

what breaks down heme iron in enterocyte

A

heme oxygenase, release CO and biliverdin

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7
Q

What happens to dietary Fe3+ before absorption

A

recuded at extracell apical membrane by ferric reductase prior to absorption

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8
Q

Fe2+ exits enterocyte how and then what happens

A

ferroportin

converted back to Fe3+ by haphaestin and binds to transferrin

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9
Q

decreased apoferritin synthesis from liver disease changes iron levels how

A

elevated serum iron levels because apoferritin is the storage mech

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10
Q

what is hepcidin and its mech

A

peptide secreted by hepatocytes that causes degradation of ferroportin to reduce dietary iron absorption

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11
Q

what occurs in loss of hepcidin production

A

hemochromatosis. Fe overload

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12
Q

what happens in increase hepatice release of hepcidin

A

anemia of chronic disease by blocking Fe absorption

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13
Q

what is first step of heme synthesis and where does it occur

A

succinyl CoA and glycing make ALA in the mitochondria

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14
Q

how and where is porphobilinogen formed

A

2 ALA via ALA dehydratase make porphiliniogen in the cytosol

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15
Q

what disorders are cause by mutations in ALA dehydratase (porphobilinogen synthase)

A

porphyria and Pb poisoning

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16
Q

sideroblastic anemia is caused by a mutation where

A

aminolevulnic acid synthase (makes ALA) in mitochondria

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17
Q

porphyria can be caused by what mutations

A

ALA dehydratase and PBG deaminase

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18
Q

where and what converts protoporphyrin to heme

A

in mitochondria

ferrochelatase

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19
Q

too much of this substance can inhibit ferrochelatase

A

lead

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20
Q

what is the rate limiting step for heme synthesis

A

ALA synthase in mitochondria

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21
Q

what gives negative feedback on ALA synthesis

A

heme

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22
Q

protoporphyria is caused by mutation where

A

ferrochelatase

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23
Q

where does globin synthesis occur

A

cytoplasm of normoblasts and reticulocytes

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24
Q

which chromosome encodes for alpha globin? beta?

A

alpha on chrom 16

beta on 11

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25
Q

disruption in balance of globin chains is called what

A

thalassemia

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26
Q

what are the embryonic forms of Hb

A

Gower I and II

II has alpha 2 globin and epsilom

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27
Q

what are the fetal forms of Hb

A

Hb portland and HbF

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28
Q

most abundant fetal form Hb

A

HbF

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29
Q

what are the adult Hb

A

HbA2 and HbA1

30
Q

most prevalent adult Hb and components

A

HbA1

2alpha and 2beta

31
Q

where does heme join globin chains

A

cytoplasm in RBC of marrow

32
Q

what is needed for normal Hb synthesis

A

Fe

33
Q

what is the functional Fe pool

A

Hb, myoglobin, enzymes

34
Q

what is the storage iron pool

A

ferritin, hemosiderin

35
Q

Hb can only bind Fe in what form

A

ferrous 2+

36
Q

how many bonds does Fe2+ make with hemoglobin

A

6
4 heme
1 globin
1 reversible to O2

37
Q

most common cause anemia

A

Fe deficiency

38
Q

how does heme iron enter enterocyte

A

endocytosis or binding then split into Fe3+ by heme oxygenase then enterocytes convert it to Fe2+

39
Q

what are the energy metabolism mech of RBC

A

glycolysis!

pentose phosphate cycle

40
Q

what is created in glycolysis in RBC

A

ATP for ion pumps and NADH for re-oxidation of Hb

41
Q

what is created in pentose phosphate cycel

A

NADPH to maintain reduced state glutathione and sulfhydryl groups

42
Q

how is hemolysis of RBC detected

A

hemoglobinemia annd hemoglobinuria

43
Q

what is Hb degraded into and by what?

A

macrophages of reticuloendothelial system into 3 parts

Fe, protoporphyrin and globin

44
Q

what happens to protoporphyrin ater heme breakdown

A

converted to biliverdin which is converted to unconjugated bilirubin

45
Q

what is methemoglboin

A

Hb carrying ferric iron, cannot carry O2 now

46
Q

hwo does body protect itself from increase methemoglobin levels

A

methemoglobin reductase from RBC

47
Q

what is sulfhemoglobin

A

partially denatured Hb

usually from sulfa containing drugs or aromatic amine drugs

48
Q

what is carboxyHb

A

CO Hb

49
Q

What is structure of HbF

A

2 alpha, 2 gamma

50
Q

how do we Tx infants with increased unconj bilirubin

A

light therapy changes trans to cis which is easily excreted in urine

51
Q

what catalyzes unconj to conj bilirbuin in SER

A

UDPGT

52
Q

When is urinary urobilinogen increased

A

hyperbilirubinemia

53
Q

when you see increased urinary bilirbuin what does this indicate

A

increased serum conjugated bilirubin

54
Q

water soluble bilirubin is same as what

A

conjugated

55
Q

What is Gilberts and findings

A

enzyme mutation impairing hepatocellular funciton
hepatic jaundice
total serum bilirubin mainly unconjugated, increased urinary

56
Q

what is Crigler-Najjar type I syndrome and findings

A

hepatic jaundice
enzyme mutation/defective conjugation
increased serum unconjugated bilirubin and increase urinary urobilinogen

57
Q

what isdubin johnson syndrome and findings

A

haptic jaundice
defective secretion from hepatocyte
increased serum conjugated bilirubin

58
Q

what can cause increase in direct and indirect bili

A

hepatitis with lowered conjugation or excretion

59
Q

what are findings of post hepatic jaundice

A

increased serum and urine conjugated bili
dec urobilin and stercobilin
clay colored stools!!!!
no urinary urobilinogen

60
Q

what causes sickle cell trait

A

missense mutation beta globin chain

position 6 valine for glutamic acid

61
Q

Hb S replaces what Hb

A

HbF

occurs around 6 mo

62
Q

what results from sickle cell disesase

A

hypozic tissue injury from microvascular occlusions from abnormal RBC shape
painful muscle aches and pains

63
Q

sickle cell patients have what level bilirubin

A

increased, may have jaundice

64
Q

what type of anemia is characteristic of thalassemias

A

microcytic hypochromic anemia with target cells!!! on peripheral smear

65
Q

what is alpha thalassemia

A

impaired produciton alpha chains

66
Q

what are types of alpha thalassemias

A

Hb H disease: 3 beta 1 alpha

Thalassemia major: loss all 4 alpha so results in hydrops fetalis

67
Q

what occurs in beta thalassemia

A

elevated HbF and A2 because impaired beta globin synthesis

68
Q

What is cooleys anemia

A

beta thalassemia major
homozygous
severe anemia that requires lifelong transfusions

69
Q

what is Tx for beta thalassemia minor

A

heterozygous

genetic counseling but really nothing

70
Q

clinical signs of beta thalaseemia

A

prominent protruding forehear and flattened nose
hyperplastic marrow?
“hair on end”

Year 2 Heme lymph (28 decks)

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