Haemopoiesis Flashcards
What is the producion of platelets known as?
thrombopoieisis
what is the function of platelets?
primary haemostasis
What is the lifespan of RBCs?
120 days
Waht is the lifespan of neutrophils?
7-8 hours
What is thel ifespan of platelets?
7-10days
What is the units for red cells?
x10^12/L
What are the units for platelets and neutrophils?
x10^9/L
What is a blast?
nucleated precursor cell
What is special about megakaryocytes?
polyploid nucleus which can divide without dividing the cyoplasm
What is a myelocyte?
nucleated precursor between neutrophils and blasts
What condition are there increased numbers of myelocytes?
chronic myeloid leukaemia
What happens when a haemopoeitic progenitor cell dvidies?
produces 2 daughter cells, but one of them is identical to parent cell= self-renewal
What is self-renewal?
a property of stem cells, lost in descendents
During steady-state haemopoiesis what happens to stem cells?
quiescent/dormant
What can myeloid mean?
marrow; lineage (non-lymphoid); granulocytes and precurosors
What germ layer are haemopoeitic stem cells derived from?
mesoderm
What is the first site of erythroid activity in the fetus
yolk sac
When does yolk sac haemopoiesis stop
week 10
When does liver haemopoeisis begin?
week 6
When does splenic haemopoiesis begin?
week 12
When does bone marrow haemopoiesis begin?
week 16
What bones does haemopoiesis take place in adults?
vertebra; sternum; rib; prox parts of long bones; skull (axial skeleton)
What are the two types of bone?
trabecular and cortical
What is the interface of bone and bone marrow?
endosteum
What non-haemopoetic cells are found within the bone marrow?
adipocytes; fibroblasts; osteoclasts; osteoblasts
what is the function of haemopoietic cells within the bone marrow?
produce cytokines to influence haemopoeissi
How does bone marrow get its blood supply?
nutrient artery and periosteal network
What do arterioles in the bone marrow drain into?
sinuses
What is the difference between capillariesand sinsuses?
sinuses are larger and have a diconstinous basement membrane
What other organs aside from bone marrow have sinusoids?
liver and spleen
What is the function of the fenestrations between endothelial cells in sinuses?
allow produced blood cells in circulation
What is release of red cells associated with?
sinusoidal dilatation; increased blood flow
How do neutrophils reach the sinusoid?
activtrly migrate by chemotaxis
What is the relationship between megakaryocytes and sinusoids?
extend long branching processes called proplatelets into vessels
What is the difference between red and yellow bone marrow?
red is haemopoieticall active whereas yellow marrow is fatty and inactive
How is % marrow cellularity calculated?
100-age = cellularity %
What is the normal myeloid:erythroid ratio?
myeloid precursors are higher due to shorter lifespan than red cell precursors
When may the myeloid:erythroid ratio change?
during haemolysis
How is haemopoiesis regulated?
intrinsic properties of cells eg transcription factors unique to certain cells; signals from microenvironment can influence intrinsic cell properties
Why does erythroid maturation occur around nurse macrophage islands?
macrophage provides growth factors nutrients for development
What is the neutrophil and its maturation regulated by?
granulocyte-colony stimulating factor
What hormone regulates megakaryocytes?
thrombopoietin
What is name for the anatomical site which haemopoietic stem cells occupy?
niche
What is the function of the niche?
provides signal for expansion; differention or dormancy aroudn vasculature- different cytokines
How can precursor cells be investigated?
bonw marrow aspirate or biospy
How is haemopoeisis of morphologically indistinguishable cells assessed?
immunophenotyping and cytochemistry
What is immunophenotyping?
identifying patterns of antigen expression unique to a cell lineage using antibodies specific to different antigens
