RBCs

Question 1

Hb Functions

Answer 1

1) O2 transportation
2) CO2 transportation
3) Buffer

Question 2

Hb factfile

Answer 2

• ~68 kDa tetrameric molecule with each globin chain surrounding the haem prosthetic group (4 haems in total)
• Has high O2 affinity where pO2 is high, but low when pO2 is low
• Conformational change adjusts O2 affinity of tetrameric Hb by varying access to/from Haem groups

Question 3

RBC structure

Answer 3

• Biconcave disc: Mean diameter ~ 7 μ, Mean volume ~ 78-101 fL
• 25% of volume is Hb, 33% of weight is Hb

Question 4

RBC membrane

Answer 4

• Bi-layered membrane, made up of 40% lipids, 52% protein + 8% carbs
• 6-10 nm total thickness

Question 5

Band 3 protein (RBC membrane)

Answer 5

Function: Anion transport, Chloride + Bicarbonate especially

Question 6

Glycophorin A (RBC membrane)

Answer 6

Function: Maintenance of negative charge, which helps with electrostatic repulsion to prevent adhesion, sugar transport

Question 7

Glycophorin B (RBC membrane)

Answer 7

Function: Regulation of cell shape, membrane deformability + membrane mechanical stability

Question 8

Ankyrin (RBC membrane)

Answer 8

Function: Links lipid bilayer to spectrin

Question 9

Spectrin (RBC membrane)

Answer 9

Function: Maintenance of biconcave disc + is the most abundant cyto-skeletal skin

Question 10

“Actin complex” (RBC membrane)

Answer 10

Function: Links lipid bilayer to spectrin

Question 11

RBC metabolism

Answer 11

• Uses anaerobic glycolysis for energy along with the pentose phosphate pathway

Question 12

RBC monitoring + destruction

Answer 12

• Has a lifespan of ~120 days
• Shortening lifespan of RBC can lead to haemolysis, but can be compensated with increased production
• Increased reticulocyte count generally means an increased rate of RBC production
• Macrophages destroy RBCs in the reticuloendothelial system