Erythropoiesis Flashcards
What is hematopoiesis?
The bodys process of making all 3 types of blood cells - rbcs wbcs platelets
What is erythropoiesis?
The bodys process of making rbcs (transport oxygen and co2)
How many rbcs will one pro erythroblast give rise to?
16 mature rbcs
What will a late (pyknotic) erythroblast mature into?
A reticulocyte and in turn a mature rbc
The evolution of the cytoplasm staining under microscope as red cell matures?
-Early normoblast - basophilic - dark blue
-Intermediate normoblast - polychromatic - lighter blue
-Late normoblast - orthochromic - light blue
-Nucleus decreases in size and is evntually extruded from the mature red cell
-Red cell - eosinophilic - salmon pink as cell becomes haemoglobinised and stains w eosin the acidic part of leishman
Is there i) nuclear dna ii) rna in cytoplasm in normoblasts, reticulocytes, mature rbcs
Nuclear dna is in normoblasts but not the other 2
RNA in cytoplasm in normoblasts and reticulocytes
What is a reticulocyte?
A young erythrocyte newly released from the bone marrow into the peripheral blood
-takes up to 48 hours to develop into mature red cell
-contains ribosomal remnants ands residual rna from erythroblast precursors
-pale blue
What stimulates red cell production?
The kidney exposed to hypoxia or anoxia states (less oxygen conc in tissues) triggers the production and release of red cell growth factor erythropoeitin
-stimulates erythropoeisis by increasing the number of progenitor cells committed to erythropoiesis
-erythropoeitin increases in anaemia
Characteristics of erythropoeitin molecule
-A sialic acid glycoprotein with alpha 1 globulin
-90% is produced in the kidney, remaining 10% produced in liver
-present in small amounts in normal plasma
-glycosylated polypeptide of 165 amino acids with a distinct electrophoretic pattern
-heat stable
-produced in response to low oxygen tension (PO2) - reduced PO2 leads to release of erythropoeitin from kidney
Conc of EPO in people living in high altitudes
-Have higher conc of EPO as require more RBCs to pick up oxygen for the tissues
What does EPO control?
-Interacts w cells that contain the EPO receptor - include red cell progenitor cells and red cell precursor cells in the bone marrow
-Effects the rate of transfer of iron to the normoblast and the rate of haem synthesis
What proportion of immature rbcs does the bone marrow have?
Pro normoblast - 1%
Early normoblast - 1-4%
Inter normoblast - 20-30%
Late normoblast - 70%
What is the myeloid/erythroid ratio
-The ratio of immature white cells to immature red cells in the bone marrow
-4:1 (white : red)
-In leukaemia and in severe infection the ratio can increase 20:1
In a vit B12 and or folate deficiency what does the bone marrow produce?
Megaloblasts - bm is megaloblastic
Hyperblastic marrow?
overproduction of cells
hypoplastic marrow?
under production of cells
Aplasia or aplastic bone marrow
no production of cells
What can be used to measure Erythropoieitic Activity?
-Full blood count
-Blood film for rbc morphology
-Bone marrow microscopy
-EPO assay - levels may be low in renal disease
-Ferrokinetics
How does ferrokinetics work?
-Use an isotope e.g Fe*59
Inject it into patient - this should be taken up by transferrin and transported to the bone marrow
-If there is normal erythropoeisis, the isotope should reappear later in the hb molecule in red cells
