Haematopoiesis Flashcards
Haematopoiesis
Production of blood cells
Erythropoiesis
Production of RBCs
Leukopoiesis
Production of white blood cells
Myelopoiesis
Production of granulocytes and monocytes
Granulopoiesis
Production of granulocytes (neutrophils, eosinophils, basophils)
Lymphopoiesis
Production of lymphocytes
Thrombopoiesis
Production of platelets
Extramedullary haematopoiesis (EMH)
Production of blood cells outside of the bone marrow
Erythropoietin
hormone produced by kidneys that regulates erythropoiesis
Thrombopoietin
Hormone produced by the liver, kidney and marrow stromal cells that regulates thrombopoiesis
Sites of leukopoiesis
Ebryo - yolk sac
foetus - liver, spleen and bone marrow
neonate - liver and bone marrow
Adult - bone marrow (spleen and liver in disease)
Regulation of myelopoiesis
Stem cell factor, colony stimulating factor and cytokines e.g. IL-6 (neutrophil), IL-5 (eosinophils), IL-3 (basophils), IL-1,3&6 (monocytes)
Lifespan of lymphocytes
2 weeks in circulation
Memory cells can last for years
Cells in miotic Pool
Myeloblasts, promyelocytes, myelocytes
Time in miotic pool
2-3 days
Number of cells in Maturation/storage pool
80%
How many days of storage does a dog have for neutrophils?
5
Regenerative left shift
Where the absolute number of mature neutrophils outnumbers the absolute number of immature neutrophils (ie bands+metamyelocytes+myelocytes). This supports an orderly marrow response to demand.
Degenerative left shift
Where the absolute number of mature neutrophils is less than the absolute number of immature neutrophils (bands+metamyelocytes+myelocytes). This supports a disorderly marrow response to demand.
Often seen in sepsis but can be seen in marrow disease such as myeloid leukaemia and myelodisplastic syndrome.
Time in maturation pool
2-3 days
Circulating pool
free flowing cells
Marginal pool
cells adherent to vessel walls through expression of adhesion molecules. Ready to migrate into tissues.
Mechanisms for increased granulopoiesis
- Recruitment of more stem cells -> neutrophils (3-5 days to increase blood neutrophils.
- Increased divisions in proliferation pool (takes 2-3 days to increase blood neutrophils)
- Hastened maturation (seen in toxic change)
- Neutrophil release stimulated by CSF, complement C5a, TNF-alpha
Lifespan of granulocytes
Neutrophils: 10-12 hours in blood 24-48 hours in tissues Eosinophils: minutes to hours in circulation lifespan unknown Basophils: 6 hours in circulation 2 weeks in tissues
Maturation of monocytes
24-36 hours
Maturation time of megakaryocyte
2-10 days
Avian and reptile thrombocytes have nuclei-true or false
true
Platelet life span and storage
5-9 days
30-40% sequestered in the spleen
