Lec 1 Hematopoesis Flashcards
What is the equation for MCV?
MCV = hematocrit / erythrocyte count (RBC x 10^6)
What is MCV?
mean corpuscular volume = average size of RBC
What is the equation for MCH?
MCH = hemoglobin / erythrocyte count (RBC x 10^6)
What is MCH?
mean corpuscular hemoglobin = average amount of hemoglobin per cell
What is life span of RBCs?
4 months
What are the components of plasma?
proteins, immunoglobulins [antibodies], clotting factors, anti-coagulants
What are the components of the buffy coat?
platelets and white blood cells
What is normal hematocrit %?
40-50%
What is the difference plasma and serum?
serum does not contain clotting factors
How do you measure hematocrit?
multiple # of RBCs x mean corpuscular volume
What is an equation for MCV?
hematocrit / erythrocyte count (RBC x 10^6)
What is an equation for mean corpuscular hemoglobin?
hemoglobin / erythrocyte count (RBC x 10^6)
What does the worse anisocytosis mean?
variation in RBC size
When might leukocyte count be falsely elevated?
in presence of clumped/aggregated platlets, nucleated RBCs, or non-lysed RBCs
When might platelet count be falsely low?
when platelets are clumped by agglutinins [pseudothrombocytopenia]
What is normal reticulocyte %?
1%
What dye can you use to stain reticulocytes?
methylene blue = stains residual RNA present in young RBCs
What is the corrected reticulocyte count?
multiple retic count x observed hematocrit / normal hematocrit
normal = 45%
What is the absolute reticulocyte count?
actual number of reticulocytes in given volume of blood
retic count x total RBC count
What does low retic count suggest?
problem with bone marrow production of RBCs
What does normal/high retic count suggest in anemia?
cause of anemia related to destruction of RBCs after they leave the bone marrow
What is myelopoiesis?
development of cells of myeloid lineage [RBCs, platelets, neutrophils, monocytes, eosinophils, basophils]
What is erythropoiesis?
development of RBCs
What is megakaryopoiesis?
development of megakaryocytes and platelets
What is lymphopoiesis?
development of cells of lymphoid lineage –> B and T cells
Where does lymphopoiesis occur in adult?
spleen
lymph nodes
thymus
gut-associated lymphoid tissue
What is sequential location of hematopoiesis in fetal development? [hint: 5 locations]
- yolk sac
- aorta-gonad mesonephros region
- liver
- spleen
- bone marrow
Wat is definitive hematopoiesis? Where does it begin?
forming nucleated RBCs which synthesize fetal hemoglobin
begins in liver
After birth where does hematopoiesis occur?
only in bone marrow
Can you see stem cells in the bone marrow?
not morphologically identifiable
one in 10^6 nucleated marrow cells is a stem cell
What is the order of cell development to form differentiated RBC?
stem cell –> multi-lineage progenitor –> uni-lineage progenitor –> identifiable precursor –> circulating mature cell
How do hematopoietic cells differ from other cells in body?
- short life span
- multiple cell ypes
- cells widely distributed throughout body
- hematopoiesis can occur quickly in emergencies
- cells must be replaced daily
How can you identify hematopoietic stem cells?
cell surface antigen CD34
How can you identify progenitor cells?
not morphologically identifiable
can use in vitro assay
cell surface antiges CD34
How can you identify precursor cells?
morphologically identifiable
What is normal distribution myeloid to erythroid precursor ratio in bone marrow?
normally 3 to 3.5:1
myeloid –> become granulocytes, monocytes, neutrophils
What is the action of stromal cells in the bone marrow?
create cellular matrix
produce cytokines and hematopoietic growth factors [HGFs]
What makes of the bone marrow extracellular matrix? Function?
fibronectin, proteoglycans, collagen
bring cytokines/growth factors and progenitor cells together
Where is erythropoietin produced?
kidney
act on bone marrow erythroid cells
Where is thrombopoietin produced?
liver
acts on megakaryocytes in bone marrow = platelet precuroors
What is action of plerixafor?
inhibits interaction between stromal derived factor 1 [SDF-1] and its receptor chemokine receptor 4 [CXCR4] –> release of hematopoietic stem cells from the bone marrow into peripheral blood
