Hemoglobin

Question 1

Hemoglobin is a ____mer

Answer 1

tetramer

Question 2

Heme =

Answer 2

proto + Fe

Question 3

Allosteric regulation

Answer 3

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

Question 4

positive cooperativity

Answer 4

binding to O2 - increase affinity for O2

Question 5

Taut configuration

Answer 5

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

Question 6

R configuration

Answer 6

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

Question 7

Oxygen dissociation curve - describe and explain

Answer 7

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

Question 8

P50

Answer 8

partial pressure at which 50% oxygen saturated

Question 9

pH decrease - shift

Answer 9

right - bonds O2 less tightly

Question 10

oxygen dissociation curve - axis and shift significance

Answer 10

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

Question 11

Temperature increase … shift?

Answer 11

right

Question 12

2,3 BPG increase - shift

Answer 12

right (2,3 BPG byproduct of anaerobic glycolytic pathway)

BPG increase = increased O2 utilization, glycolysis, chronic hypoxia, chronic anemia

Question 13

Embryonic hgb

Answer 13

hgb gower 1, grower 2, portland

Question 14

Fetal Hgb

Answer 14

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

Question 15

Adult Hgb

Answer 15

A2B2

Question 16

HbA2 elevated= suggests?

Answer 16

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

Question 17

Hemoglobin structural differences explanation

Answer 17

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

Question 18

Phsyiological effect of altered O2 affinity

Answer 18

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

Question 19

What is methemoglobinemia?

Answer 19

Fe3+ state in hemoglobin

Question 20

Biology of methemoglobinemia formation

Answer 20

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

Question 21

Methemoglobinemia etiology

Answer 21

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)

Question 22

Diagnose methemoglobinemia

Answer 22

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

Question 23

Treatment of methemoglobinemia

Answer 23

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

Question 24

CO poisoning

Answer 24

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

Question 25

CO poison treatment

Answer 25

Hyperbaric oxygen, 100% oxygen to compete CO binding site

Question 26

CO poison diagnosis

Answer 26

Co-oximetry | pulse-OX will NOT work!

Question 27

CO posion diagnosis

Answer 27

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

Question 28

Pulse Oximeter - how does it work?

Answer 28

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,