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B&L 1 > Hemoglobin > Flashcards

Hemoglobin Flashcards

1
Q

in what form must iron be to bind oxygen?

A

reduced - ferrous

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2
Q

what is hemoglobin with iron in ferric form called?

A

methemoglobin

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3
Q

which enzyme reduces iron

A

cytochrome b5 reductase

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4
Q

confirmation of deoxy hemoglobin?

A

taut (T)

due to salt bonds, hydrogen bonding, and hydrophobic interactions

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5
Q

confirmation of oxy hemoglobin

A

relaxed - binding oxygen causes taut bonds to progressively break
(R)

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6
Q

p50 of HbA at standard conditions

A

27mmHG

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7
Q

2,3BPG is by-product of?

A

anaerobic glycolysis

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8
Q

2,3BPG binds?

A

pocket between beta chains, stabilizing hgb in deoxygenated T state –> decreased O2 affinity –> right shift

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9
Q

cardiac left to right shunt –> 2,3bpg?

A

increased 2,3 bpg –> right shift

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10
Q

severe anemia –> 2,3bpg?

A

increase

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11
Q

septic shock –> 2,3bpg?

A

decrease

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12
Q

hpophophatemia –> 2,3bpg

A

decrease

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13
Q

congestive heart failure –> 2,3bpg

A

increase

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14
Q

bpg mutase deficiency –>

A

decrease in 2,3bpg

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15
Q

hepatic cirrhosis –> 2,3bpg

A

increase

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16
Q

transfusion of stored blood –> 2,3bpg

A

decrease

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17
Q

severe acidosis –> 2,3bpg

A

decrease (because beyond bohr effect)

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18
Q

methemoglobinema - curve shift?

A

left

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19
Q

carbon monoxide poisoning - curve shift?

A

left

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20
Q

fetal hemoglobin?

A

alpha2gamma2

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21
Q

when does fetal hemoglobin dominate

A

after 8 weeks

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22
Q

does Hgb F bind 2,3BPG better or worse than adult?

A

worse

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23
Q

fetal curve relative to adult

A

left

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24
Q

Hemoglobin A2

A

alpha2/delta2
2% adult
functions like HgbA except more heat stabile and slightly higher affinity for O2

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25
Q

HgbA2 elvated in?

A

beta thalassemia
sickle cell
hyperthyroidism
megaloblastic anemia

26
Q

unstable hemoglobins have tendency to spontaenously denature often due to mutations that disrupt the stablility of?

A

the heme-globin linkage

27
Q

untable hemoglobins may lead to

A

hemolytic anemia
with
jaundice and splenomegaly

28
Q

unstable hemoglobins can be referred to as?

A

Heinz body anemia

29
Q

hemoglobin koln

A

unstable
one of the most common
mutation in beta
increased affinity (left)

30
Q

hemoglobin poole

A

unstable hemoglobin
gamma chain mutation
infants with hemolytic anemia - which resulsove within a few months becasue you no longer make gamma

31
Q

do unstable hemoglobins usually need blood transfusions?

A

no

32
Q

unstable hemoglobin treatment

A

folic acid

  • splenectomy is not curative
  • may not see Heinz bodies until after splenectomy
33
Q

Hemoglobin chesapake

A

high affinity

alpha globin chain

34
Q

altered oxygen affinity hemoglobins and their stabilty

A

usually stable

35
Q

altered oxygen affinity hemoglobins and electrophoresis

A

usually abnormal

36
Q

altered oxygen affinity hemoglobins and hemolysis

A

usually none

37
Q

high oxygen affinity variants and tissue oxygenation

A

leads to hypoxia –> leads to EPO production by kidney –> increased RBC count
*generally no treatment need

38
Q

low O2 affinity Hb
anemia?
presenation?

A

mild anemia

cyanosis

39
Q

cyanosis most common cause?

A

deoxygenated hemoglobin - not necessarily hypoxia

40
Q

differential dx

cyanosis and globins (3)

A

too much deoxy
too much methemoglobin
sulfhemoglobinemia

41
Q

differential dx of cyanosis:

inadequate O2 of Hb (5)

A 
pulmonary disorders
cardiac right to left shunt
congestive heart failur
cardiovascular collapse (shock)
low o2 affinity Hb variant
42
Q

differenital
methemoglobinemia
(5)

A 
congenital 
cytochrome b5 reductase deficiency 
cytochrome b5 deficiency 
M hemoglobins
Acquired (drugs / toxins)
43
Q

differential sulfemoglobinemia

A

acquired (drugs/toxins)

44
Q

methemoglobinemia

A

Fe3+ cannot carry oxygen
curve shifts left
p50 goes down
1% is normal

45
Q

color of methemoglobin

A

chocolate :)

46
Q

congential methhemoglobinemia

A

cytochrome b5 reductase deficiency (autosomal recessive)

47
Q

congential methemoglobinemia - clinical

A

increased o2 affinity
blue and well at birth (will be blue but does not affect qol)
up to 40% methemoglobin
asymtpomatic heterozygotes unless oxidant expozed

48
Q

hemoglobin M

A

autosomal dominant

mutation in a or b chain making fe3+ resistant to reduction

asymptomatic cyanosis

normal amount of hemoglobin with mild hemolysis

abnormal electrophoresis - M band

49
Q

acquired methemoglobinemia

potential ways to aquire (2)

A

drugs

well water

50
Q

acquired methemoglobinemia when and what to treat with?

A

if level is greater than 40% and there are symtpoms - give methylene blue (an artificial electron acceptor)

51
Q

methemoglobin (acute vs chornic?)

A

acutely ill will yield problems - give methylene blue

chronic not so much

52
Q

hemoglobin F

is it oxidized more or less readily to ferric state

A

more readily

53
Q

cytochrome b5 reductase activity in first few months of life?

A

low

54
Q

what might cause a bambino to be cyanotic?

A

well water
raw spinach
disinfectants
benzocaine

55
Q

CO poisoning
affinity?
curve shift?

A

more affinity (240x)
shift left
* so you are not only outcompeting hemoglobin for oxygen binding but you are making it more difficult for the hemaglobin that has successfully bound oxygen to release it)

56
Q

CO poisoning… more or less of leftward shift than mehemoglobin?

A

more

57
Q

what color are CO people?

A

cherry red?

58
Q

CO poisoning treatmetn

A

100% O2/hyerbaric chamber

59
Q

How do we assess oxygen saturation?

A

arterial blood gas (traditionally)

now we use pulse ox

60
Q

how does pulse ox work?

A

photo detector and tow light emitting diodes
640 deoxy absorption
940 oxy absorption

61
Q

ideal ox sat?

A

90s or 100

16000 ft? low 80s

B&L 1 (5 decks)

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