Haemopoeisis Flashcards
what are the mature blood cell types
red cells
-erythrocytes
platelets
White cells
- Granulocytes (neutrophils, eosinophils, basophils)
- monocytes (macrophages)
- lymphocytes (B cells, T cells, NK cells)
what makes up haemopoeissi
erythropoeiss
thrombopoeisis
myelopoeisis or granulopoesis
ly,pjopoiesis
what is the lifespan of red cells
120 days
2.5 million are lost and produced per second to maintain levels
what is the lifespan of neutrophils
7-8 hours
1-2 million per second re lost and produced
what is the lifespan of platelets
7-10 days
1 million platelets are made every second
how are platelets formed
budding of megakaryocytes
what are reticulocytes
immediate RBC precurosors ‘polychromasia’
what are myelocytes
nucleated precursor between neutrophils and neutroblasts
what are ‘ blast’ cells
nucleated precursor cells
erythroblasts
myeloblasts
what is the first cell in haemopoeisis
haemopoeitic stem cell
4 general stages of haemopoesis
Stem cells
multipoint progenitors
oligolineage progenitors
mature cells
What are the developmental events/stages in haemopoiesis
self-renewal (need to create more stem cells)
proliferation (increase in numbers)
differentiation (descendants commit to one or more lineages)
maturation (descendants acquire functional properties and stop proliferating)
apoptosis (descendants undergo cell death)
what are the sites of haemopoesis in the fetus
yolk sac - first side of erythroid activity, stops by week 10
Liver starts at week 6
bone marrow takes over at week 16
where do haemopoeitic cells come from embryonically
the mesoderm
where is haemopoeisis in adults
bone marrow within
axial skeleton
pelvic
long bones
where do you take a bone marrow biopsy in a child vs and adult and why
child - femur/tibia as that is where the most haemopoesis occurs
adults - posterior iliac crest as that is where the most haempoeisis occurs
older people - vertebrae, sternum and ribs have the most haemopoesis
what is bone marrow
a complex organ surrounded by a shell of bone with a neuromuscular supply
What are the microscopic compartments of the bone marrow
Cellular (haemopoeitic cells and non-haemopoeitic cells - adipocytes, fibroblasts, osteoclasts, osteoblasts)
connective tissue matrix
vascular elements
how is blood supplied to the bone marrow
‘Venous sinuses’
arterioles drain into ‘sinuses’ which are wide venous vessels opening into a larger central sinus
difference between sinuses and capillaries
sinuses are larger and have a discontinuous basement membrane (lots of gaps in it)
what are the gaps between endothelial cells in the bone marrow sinus’s called
fenestrations
how do mature cells leave the marrow and enter the circulation
pass through fenestrations into the venous sinus
release of red cells causes dilation of the sinuses and increased blood flow
how do neutrophils get into the bone marrow sinuses
active migration
how do platelets get into the venous sinuses
megalokaryocytes extend long branching processes (proplateletes) into the sinusoidal blood vessel
what is the difference between red and yellow marrow
red marrow - haemopoietically active
yellow marrow - fatty haemopoietically inactive
what happens to bone barrow due to ageing
increase of yellow marrow with age resulting in a reduction in marrow cellularity in older people
what is the myeloid:erythroid ratio
relationship of neutrophils and precursors to proportion of nucleated red cell precursors
(is reserves in haemolysis as a compensatory response)
usually between 1.5:1 and 3.3:1
what regulates haemopoiesis
intrinsic properties of cells (eg. stem cells vs progenitor cells vs mature cells)
signals from immediate surroundings and periphery (microenvironmental factors)
specific anatomical area (niche) for optimal developmental signals
what regulates neutrophil precursor maturation
G-CSF
granulocyte colony stimulating factor
what regulates growth and development of megakaryocytes
thrombopoietin
what microenvironmental factors regulate haemopoiesis
the niche environment which the cell is in
different cytokines in the environment
Nice environment is altered in disease states or with therapy
investigations for haemopoeiss
Blood count
Cell indices
morphology
less common - specialise bone marrow examination
investigations for mature cell counts
non-lymphoid cells - blood count/morphology is sufficient
lymphoid cells often need immunophenootyping using specific antibodies to tell what lineage or stage of development they are
what is immunophenotyping
identifying patterns of protein (antigen) expression unique to a cell lineage
use antibodies (in combination) specific to the antigens
