Erythropoiesis

Question 1

define erythropoiesis

Answer 1

process of making red blood cells

Question 2

how many erythrocytes are produced from one pro erythroblast

Answer 2

16 mature rbcs

Question 3

what do erythroblasts mature into before maturation to a rbc

Answer 3

reticulocyte

Question 4

discuss the appearance of precursor RBCs under the microscope

Answer 4

1. early normoblast = basophilic
2. intermediate normoblast = polychromatic (stains lighter blue)
3. late normoblast = orthochromic (light blue)
4. RBC = eosinophilic (salmon pink)

Question 5

what is a reticulocyte

Answer 5

young erythrocyte which is newly released from the marrow into blood. takes 48 hrs for it to mature in the blood. they have ribosomal and RNA remnants from the erythrocyte precursors

Question 6

what effect has anoxia/hypoxia on RBC production

Answer 6

when there is less O2, RBC production is stimulated by an increase in erythropoeitin from kidney. this causes an increase in the number of progenitor cells that commit to erythropoeisis .

*you will see an increase of erythropoietin in anaemia

Question 7

write about the characteristics of EPO

Answer 7

• is a sialic acid glycoprotein with alpha 1 globulin
• 90% produced in liver, 10% kidneys
• glycosylated polypeptide of 165 amino acids and has a distinct electrophoretic pattern
• heat stable

Question 8

what is PO2

Answer 8

O2 tension

Question 9

apart from rbc synthesis, what else does EPO affect

Answer 9

the rate of iron transfer

Question 10

what are the proportions of red cell precursor in marrow

Answer 10

pro normoblast: 1%
early normoblast: 1-4%
inter. normoblast: 20-30%
late nomoblast: 70%

Question 11

what is the myeloid/erythroid ratio

Answer 11

ratio of immature white cells to immature red cells in the marrow

Question 12

what is the normal myeloid/erythroid ratio

Answer 12

4:1

this is due to the lifespan of white cells compared to red

Question 13

what is the myeloid/erythroid ratio commonly seen in leukaemia

Answer 13

20:1

Question 14

in what condition may the erythroid count be larger than the myeloid in the myeloid/erythroid ratio

Answer 14

severe blood loss/haemolytic anaemia/ red cell destruction

Question 15

what is megaloblastic

Answer 15

where a B12 or folate deficiency produces megaloblasts instead of normoblasts

Question 16

what does aplasia/aplastic marrow mean

Answer 16

no production of cells in the bone marrow

Question 17

what occurs in B12/folate deficiency for cells to become macrocytic

Answer 17

where one or more mitotic steps are omitted

Question 18

how is EPO measured

Answer 18

• full blood count
• blood film (cell morphology)
• bone marrow microscopy
• EPO assay (good for detecting low levels caused by renal disease)
• Ferrokinetics: where isotope i.e Fe59 is injected into patient and is taken up by transferrin which takes it to the marrow. With normal EPO production the isotope should be seen in Hb later in RBCs