Life and Death of RBCs

Question 1

Erythropoiesis

Answer 1

Production of the RBCs in bone marrow

Question 2

Proerythroblast

Answer 2

First stage

Committed to becoming an RBC once it has receptors for EPO

Question 3

Normoblast

Answer 3

Last nucleated stage of RBC formation

Question 4

Reticulocyte

Answer 4

After expulsion of nucleus
Released from the bone marrow ~2 days later
Become a fully mature RBC about 24 hours after that

Question 5

Erythropoietin

Answer 5

Glycoprotein hormone
Synthesized and secreted by the kidney (and a bit by the liver)
Increased when blood O2 concentrations fall
Essential cytokine for RBC precursors in marrow

Question 6

2 reasons for the biconcave shape of RBCs

Answer 6

Maximizes surface area

Allows the hemoglobin to be close to the cell surface

Question 7

2 functionally significant protein groups with the lipid bilayer

Answer 7

Integral membrane proteins

Peripheral membrane proteins

Question 8

2 Integral membrane proteins and their functions

Answer 8

Glycophorin C: maintains RBC shape
Band 3: links plasma membrane to cytoskeleton
Both are critical to RBC shape and stability

Question 9

3 Peripheral membrane proteins

Answer 9

Spectrin
Protein 4.2
Ankyrin

Question 10

When does Hb synthesis occur?

Answer 10

Prior to nucleus extrusion

Question 11

2 main proteins in Hb

Answer 11

Globin (2 beta and 2 alpha chains)

Heme (with Fe inside)

Question 12

Heme groups

Answer 12

Covalently bound to globins
Fe in porphyrin ring
Fe reversible binds O2

Question 13

Where does
1. CO2
2. CO
bind?

Answer 13

1. To the Hb protein chains

2. Competes with O2 for Fe

Question 14

2 Major enzymatic pathways in the RBC

Answer 14

Pentose Phosphate Pathway

Glycolysis

Question 15

Reduced glutathione

Answer 15

Prevents membrane lipid oxidation
Prevents globin oxidation and denaturation
Detoxifies oxidants

Question 16

Pyruvate kinase

Answer 16

Key glycolytic enzyme

Tight regulation is really important for glycolysis and ATP production