RBC physiology & function

Question 1

What are the ways the function of Hb can be altered (4)

Answer 1

• amount of Hb produced
• Structure “””
• stability “””
• function “””
• 2+ can affect each other => compound effect

Question 2

What’s how does thalassemia affect Hb function? And how it occurs

Answer 2

• Decrease production => Low Hb made

- due to mutation in globin genes (alpha = a thalassemia or beta= B thalassemia)

Question 3

What’s how does haemoglobinopathies affect Hb function?

Answer 3

alters Hb Structure & function

Question 4

Outline how the presence of haemoglobin S may affect the haematological characteristics of an individual

Answer 4

HbS forms bc glutamic acid is replaced valine @ 6th position on B-chain => sickle cell shape (when deoxygenated)

Question 5

Where & how haeme & globin is formed to form haemoglobin?

Answer 5

• in the mitochondria of RBC.
• Fe2+ binds to prtoporphyrin IX ring & the center
• transported to the cytoplasm to combine w/ globin
• globin tetramer made in cytoplasm w/in polyribosomes: alpha + non-apla (beta or gamma)
• ratio of haeme & globin should be close to 1:1 ratio
• goblin tetramer + haeme = haemoglobin

Question 6

Where & how is globin formed?

Answer 6

in the cytoplasm of RBC

Question 7

Which stage in life are primitive haemoglobin, HbF and HbA predominant.

Answer 7

• Embryo: primitive Hb
• Foetus: HbF
• 6 months old: HbA (if things are normal)

Question 8

Why is the Embden-Meyerhofglycolytic pathway necessary for RBC function?

Answer 8

• must have glycolytic pathway => energy (2 ATP / glucose)

Question 9

Why is the hexose monophosphate shunt necessary for RBC function?

Answer 9

• use ~10% glucose to produce NADPH => reduced glutathion (GSSG) w.\/ glucose-6-phosphate dehydrogenase
  > protect RBC from oxidative damag

Question 10

Why is the Leubering-Rapaport shunt necessary for RBC function?

Answer 10

form 2,3-biphosphosphoglycerate (2,3 BPG)

> modify Hb affinity for O2

Question 11

Why is the methaemoglobin (metHb) reductase necessary for RBC function?

Answer 11

rapidly convert metHb (Fe3+) to Hb (Fe2+) so Hb remains functional

Question 12

What happens when there is a deficiency in glucose-6-phosphate dehydrogenase?

Answer 12

RBC can’t make reduced glutathione susceptible to oxidative damage => Hb denatured => heinz bodies
- so body increases erythropoiesis to compensate for RBC lost

Question 13

measurement of Hb

Answer 13

1. mix sample w/ Drabkin’s reagent
2. reagent binds to Hb => cyanohaemaglobin (HbiCN)
3. measure absorbance @ 540nm => [Hb}