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Flashcards in Hemoglobin Deck (28)
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1

Hemoglobin is a ____mer

tetramer

2

Heme =

proto + Fe

3

Allosteric regulation

once a site is bound, affect affinity of another site to bind

4

positive cooperativity

binding to O2 - increase affinity for O2

5

Taut configuration

T - inter/intrasalt bonds - O2 concentration is low, 0/4 sites occupied

6

R configuration

an oxygen binds ato a site, hgb changes to increase affinity for O2

7

Oxygen dissociation curve - describe and explain

sigmoidal; due to positive cooperativity (myoglobin is hyperbola - monomer)

8

P50

partial pressure at which 50% oxygen saturated

9

pH decrease - shift

right - bonds O2 less tightly

10

oxygen dissociation curve - axis and shift significance

y = O2 sat; X = partial pressure; Right = binds O2 less; Left shift = increase affinity - binds tigheter

11

Temperature increase ... shift?

right

12

2,3 BPG increase - shift

right (2,3 BPG byproduct of anaerobic glycolytic pathway)
BPG increase = increased O2 utilization, glycolysis, chronic hypoxia, chronic anemia

13

Embryonic hgb

hgb gower 1, grower 2, portland

14

Fetal Hgb

alpha 2 gamma 2 - binds 2,3BPG poorly --> R state = increase affinity for O2

15

Adult Hgb

A2B2

16

HbA2 elevated= suggests?

beta thal, sickle cell trait/disease, hyperthryoidism, megaloblastic anemia

17

Hemoglobin structural differences explanation

taut/relaxed configuration - inter/intra salt bonds within molecules
Once O2 binds -> R state -> easier to bind others

18

Phsyiological effect of altered O2 affinity

allows O2 to be released in low pO2 (tissue) and O2 picked up in high pO2 (lungs)

19

What is methemoglobinemia?

Fe3+ state in hemoglobin

20

Biology of methemoglobinemia formation

reduced ability to convert Fe3+ to Fe2+ (ferric to ferrous) via NADPH reductace pathway

21

Methemoglobinemia etiology

Acquired: Drugs, free radicals, H2O2, HNO3, OH-, CYP B5 decreases
Genetic: homogenous deficiency of cytochrome B5 reductase - humtantion in hemoglobin -> Hgb M (alpha/beta chain defect - inhibition of reduction of Fe3)

22

Diagnose methemoglobinemia

cyanotic, but arterial pO2 normal on ABG; dark blood even with O2 exposure

23

Treatment of methemoglobinemia

methylene blue/ascorbic acid, remove cause (if any)

24

CO poisoning

CO binds 240x stronger --> carboxyhemoglobin --> allosteric change --> increase O2 affinity for hem = decrease O2 delievery to tissue

25

CO poison treatment

Hyperbaric oxygen, 100% oxygen to compete CO binding site

26

CO poison diagnosis

Co-oximetry
pulse-OX will NOT work!

27

CO posion diagnosis

headache, malaise, nausea, seizure, coma, mycardial infarction, loss of cognition, personality change, movement disorder

28

Pulse Oximeter - how does it work?

2 diodes emit 660 and 940 nm; deoxyhemoglobin max at 660, oxyhemoglobin at 940; comapre differences
inaccurate - nail polish, high motion, dark skin, anemia, shock, abnormal hemmorrhage,