Haemopoiesis Flashcards
what does intramedullary haemopoiesis mean
haemopoiesis occurring in the bone marrow
where else may haemopoiesis occur in certain pathological conditions
liver, lymph nodes and spleen
where does haemopoeisis occur in embryo
yolk sac - area vasculosa (in blood islands)
where are foetal precursor blood cells found
dorsal aorta
when does mesoblastic phase occur and what is it
week 2-3 gestation, is the period of embryonic blood formation
what are the three haemopoiesis stages
mesoblastic/embryonic
hepatosplenic phase
myeloid/bone marrow phase
what is produced during the primitive haemopoiesis stage
mostly erythrocytes, and primitive haemoglobin (gower and portland) begin to form
what occurs during hepatosplenic phase
involves the liver- main form of haemopoiesis at 4 months, and tyoe of production declines towards birth. production also occurs in the spleen to a lesser extent
what type of Hb is produced during hepatosplenic phase
HbF
when does the myeloid phase begin
5-9 months in foetus and continues through life.
what happens when myeloid phase begins in foetus
production of HbA (main adult type of Hb)
what bones contain marrow for haemopoeisis
sternum, hips, pelvis, ribs, vertebrae, femur, cranium (skull)
what is the normal ratio of fat to haemopoietic cells in adults
1:1
how many cells are produced in the bone marrow in healthy young adults
5-10 x 10^11
what factors affect haemopoeisis
growth factors, cytokines, environmental factors, o2 levels in body
what is the lifespan of mature granulocytes in blood
few hous
what is the precursor stem cell
haemopoietic pluripotent stem cell
what are the two characteristics of stem cells
- ability to proliferate and create more cells
- self renewal
what are the stages in haemopoeitic cell development
- stem cell
- differentiation and lineage selection
- maturation: non dividing cells will develop in mature cells
- functional mature cells
- cell death- apoptosis
describe multipotent colony forming units (CFU-GEMM)
these cells proliferate and differentiate into mature cells of various myeloid lineages
what are uni potent progenitor cells
CFU-E that produce cells that mature into erythrocytes
what is a rich source of stem and progenitor cells apart from marrow
umbilical cord blood
where can stem cells be found
among cells that have the CD34 cell markers. some drugs can increase CD34 production as it tells where stem cells are available to be harvested
what regulates haemopoeisis
haemopoietic growth factors (glycoprotein hormones) regulate prolif and differentiation, and regulate balance between haemopoiesis and apoptosis. they react to external stresses i.e blood loss/infections
they bind to surface receptors on target cells and trigger replication, differentiation and functional activation
