Normal Hematopoiesis Flashcards
tissues of the hematopoietic system
-bone marrow and all blood corpuscles
-liver
-spleen
-lymph nodes
-thymus
bone marrow
*hollow spaces of bones filled with all blood cell precursors
bone marrow cellularity & aging
*infancy: cellularity is 100%
*cellularity decreases by 10% with each decade of life
*around age 70-80, cellularity remains at 20-30%
*general rule of thumb for bone marrow cellularity: 100 - age of patient
normal production of bone marrow
*normal myeloid to erythroid ratio is 3:1
*controlled growth with increase in activity based upon demand [infection, low tissue oxygenation, etc]
*ACTIVITY IS DECREASED WHEN DEMAND IS MET (return to steady state bone marrow production)
*mediated by growth factors
*increase in production results in greater numbers of mature cells and some young cells, but no immature cells are released
stromal matrix of bone marrow
*stromal cells [fibroblasts, fat cells, endothelial cells]
*adhesion molecules
*growth factors
hematopoiesis during embryogenesis
*hematopoiesis begins early (week 3)
*mesenchymal cells either become endothelial cells or blood cells
site of hematopoiesis in the first 6 weeks of gestation
yolk sac
site of hematopoiesis 6-18 weeks of gestation
liver
site of hematopoiesis 18-30 weeks of gestation
liver and spleen
site of hematopoiesis 30 weeks of gestation to birth to 8 week old infant
liver, spleen, and bone marrow
site of hematopoiesis > 10 weeks postnatal
bone marrow ONLY
normal erythropoiesis: stages of red cell maturation
- pronormoblast
- basophilic normoblast
- polychromatophilic normoblast
- orthochromatic normoblast
- reticulocyte
- mature red blood cell
normal erythropoiesis: how does the CELL SIZE change during maturation from a pronormoblast to a mature RBC?
cell size DECREASES with maturation
normal erythropoiesis: how does the NUCLEUS change during maturation from a pronormoblast to a mature RBC?
*nucleus is always ROUND
*chromatin condenses with maturation
*nucleus:cytoplasm ratio DECREASES with maturation
*ultimately, the nucleus disappears
normal erythropoiesis: how does the CYTOPLASM change during maturation from a pronormoblast to a mature RBC?
*basophilia (blue cytoplasm) = immaturity
*magenta = as maturation occurs and hemoglobin accumulates
*no granules