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hemoglobin Flashcards

1
Q

hemoglobin (hb) is composed of

A

4 polypeptide subunits
2α and 2β
1 heme in every polypeptide

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2
Q

hemoglobin (hb) is exists in how many and which forms

A

2 forms

T form and R form

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3
Q

hemoglobin (hb) - T form properties

A

Taut form
deoxygenated
low affinity for 02

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4
Q

hemoglobin (hb) - R form properties

A

Relaxed
oxygenated
high affinity for 02 (X300)

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5
Q

hemoglobin (hb) - properties

A
  1. positive cooperativity

2. negative allostery

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6
Q

hemoglobin (hb) - positive cooperativity

A

tetrameric Hb molecule can bind 4 02 molecules and has higher affinity for each subsequent O2 molecule bound

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7
Q

substance that favor taut form over relaxed form (shift curve to right)

A

INCREASED CL-, H+, CO2, 2,3-BPG, TEMPERATURE

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8
Q

fetal hemoglobin subunits

A

2α and 2γ

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9
Q

fetal hemoglobin vs adult (about function)

A

loewer affinity for 2,3-BPG than adult hemoblobin and thus higher affinity for O2

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10
Q

hemoglobin aslo act as

A

a buffer for H+ ions

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11
Q

buffer for H+ ions

A

hemoglobin

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12
Q

hemoglobin modifications - types

A
  1. methemoglobin

2. carboxyhemoglobin

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13
Q

hemoglobin modifications lead to

A

tissue hypoxia from decreased O2 saturation and decreased 02 content

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14
Q

hemoglobin - normal iron status

A

resuced state Fe2+

FERROUS

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15
Q

ferrous hemoglobin

A

Fe2+

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16
Q

ferric hemoglobin

A

Fe3+

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17
Q

methemoglobin

A

oxidized form of Hb (ferric, F3+)

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18
Q

methemoglobin vs normal hemoglobin - iron status

A

normal: resuced state Fe2+ (FERROUS)
methemoglobin: oxidized state Fe3+ (FERRIC)

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19
Q

methemoglobin properties

A
  • it does not bind 02 as readily

- it has increased affinity for cyanide

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20
Q

methoglobinemia may present with

A
  1. cyanosis 2. chocolate-colored blood
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21
Q

methoglobinemia can can be treated with

A
  1. methylene blue

2. vitamin C

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22
Q

how to treat cyanide poisoning (and the mechanism)

A

nitrites followed by thiosulfate

nitrites: hemoglobin –> methoglobin which bind cyanide
thiosulfate: to bind cyanide, forming thiocyanate , which is renally excreted

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23
Q

methoglobinemia may be used

A

to treat cyanide poisoning

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24
Q

substance that cause poisoning by oxidizing F2+ to F3+ (found in)

A
  1. nitrites (from dieaary intake or polluted/high altitude water)
  2. benzocaine
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25
benzocaine poisoning
F2+ to F3+
26
nitrites poisoning
F2+ to F3+
27
methylene blue is used to
treat methoglobinemia
28
carboxyhemoglobin
form of hemoglobin bound to CO in place of o2
29
CO binds to Hb in the place of ...
O2
30
carboxyhemoglobin causes
decreased oxygen binding capacity with left shift in oxygen hemoglobin dissociation curve
31
carboxyhemoglobin effect on curve
left shift in oxygen in oxygen-hemoglobun (and decreased plateau)
32
carboxyhemoglobin causes in tissues
decreased O2 unloading in tissues
33
CO vs O2 on Hb
CO binds competitively to Hb and with 200X greater affinity than
34
carboxyhemoglobinemia treatment
100% 02 and hyperbaric 02
35
how to treat methemoglobinemia
methylene blue
36
oxygen-hemoglobin dissociation curve -shape and why
sigmoidal shape due to positive cooperativity
37
Myoglobin - structure, properties
Myoglobin monomeric and thus does not show positive cooperativity
38
Myoglobin - oxygen-hemoglobin dissociation curve
curves lacks sigmoidal appearance
39
right shift of oxygen-hemoglobin dissociation curve causes
decreased affinity of Hb for O2
40
right shift oxygen-hemoglobin dissociation curve - purpose
facilitates unloading of 02 to tissue
41
oxygen-hemoglobin dissociation curve with fetal hemoglobin and mechanism
Fetal Hb has higher affinity for 02 than adult Hb, so its dissociation curve is shifted left
42
oxygen-hemoglobin dissociation curve shift factors
1. H+ 2. CO2 3. Exercise 4. 2,3-BPG 5. Altitude 6. Temperature increased --> right shift decreased --> left shift
43
02 content = | equation
``` O2 content = (O2 binding capacity x saturation) + disolved O2 = (1.34xHbxSaO2) + (0.003xPaO2) SaO2=arterial 02 saturation PaO2=partial pressure of 02 (0.003xPaO2) = dissolved oxygen (1.34xHb) = oxygen binding capacity ```
44
normally 1 g Hb bind .... 02
1.34 ml
45
normal amount of Hb in blood
15g/dL
46
cyanosis results when
deoxygenated Hb > 5 g/dL
47
02 binding capacity (calculation and result)
O2 binging capacity = normal amount of Hb in blood x 1.34 ml = 15g/dL X 1.34ml = 20.1 ml 02/dL
48
02 binding capacity (result) (normally)
20.1 ml 02/dL
49
decreased Hd --> O2 content of arterial blood?
decreased
50
decreased Hd --> O2 saturation?
no change
51
decreased Hd --> arterial PO2?
no change
52
02 delivered to tissues (equation)
02 delivered to tissues = cardiac output x O2 contain of blood
53
CO poisoning - Hb concentration?
normal
54
anemia - Hb concentration?
decreased
55
polycythemia - Hb concentration?
increased
56
CO poisoning - % saturation of Hd?
decreased
57
anemia - % saturation of Hd?
normal
58
polycythemia - % saturation of Hd?
NORMAL
59
CO poisoning - dissolved O2 (PaO2)?
normal
60
anemia - dissolved O2 (PaO2)?
normal
61
polycythemia - dissolved O2 (PaO2)?
normal
62
CO poisoning - total 02 content?
decreased
63
anemia - total 02 content?
decreased
64
polycythemia - total 02 content?
increased
65
polycythemia - % saturation of Hd?
NORMAL
66
CO vs O2 binding on Hb (affinity?)
CO has x200 greater affinity
67
Dissolved O2 in blood - equation
0.003 x PaO2

respiratory (27 decks)

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