Haematopoeisis Flashcards
what are ‘blasts’
primitive nucleated precursor
what are megakaryocytes
platelet precursor, polyploidy
what are reticulocytes
immediate red cell precursor
what are myelocytes
nucleated precursor between neutrophils and blasts
what are the precursors or precursores
haemopoietic progenitor cell
what cells come from myeloid stem cells
red cells, platelets, granulocytes, macrophages
what cells come from lymphoid stem cells
dendritic cells, T cells, NK cells, B cells
what are the developmental events in haemopoiesis
self renewal-a property of stem cells lost in descendents
proliferation-increase in numbers
differentiation-descndents commit to one or mor elineages
maturation-descendents acquire functional properties and may stop proliferating
apoptosis-descendents undergo cell death
in general more primitive progenitors-eg stem cells are what in the steady state
quiescent
where are haemopoeitic cells derived from embryologically
mesoderm
what are the sites of haemopoiesis
yolk sac-stops by week 10
liver start by week 6
spleen by week 12
bone marrow by week 16
what do arteries feed into
sinusoids
what are sinusoids
specialised venules that form a reticular network of fenestrated (with apertures) vessels
what is the interface of bone and marrow called
endosteum-covered in bone lining cells inc osteoblasts and osteoclasts
formed red blood cells pass through what part of endothelial cells to enter ciruculation
fenestrations
how are neutrophils released from the marrow
actively migrate towards the sinusoid
how are megakaryocytes release from marrow t
they extend long branching processes called proplatelets into the sinusoidal blood vessels
what is the release of red cells associated with
sinusoidal dilatation and increased blood flow
what is red vs yellow marrow
red=haemopoietically active
yellow=fatty, inactive
how do levels of red and yellow marrow change with age
increase in yellow marrow with age and reduction in marrow cellularity in older individuals
how is marrow cellularity calculated
100-age=% cellularity
what is chemotaxis
can migrate to areas of inflammation
haemoglobin is what type of protein
allosteric protein
what is the Haldane effect
oxygenation of haemoglobin decreases its affinitiy for CO2
what is the bohr effect
h+ ions and CO2 added to the blood cause a reduction in the oxygen binding affinity for Hb
