Haemopoiesis Flashcards
definition of Haemopoiesis?
formation of blood cells
Give the 3 main types of blood cells and their subgroups and functions?
Red cells
Erythrocytes- transport O2/Co2
Platelets
Primary Haemostasis
White cells
Granulocytes
-Neutrophils, phagocytosis + acute inflammation
-Eosinophils, destroy parasites + modulate hypersensitivity reactions
-Basophils, modulate hypersensitivity rections
Monocytes --> Macrophages modulate immune reactions Phagocytic clearance Lymphocytes regulatory functions
Lymphocytes
- B cells, produce antibodies
- T cells, cell mediate immunity + regulatory functions
- NK cells, anti viral/tumour
describe what kind of nucleus granulocytes have
segmented
state the lifespan of RBCs, Neutrophils & platelets?
-why is this relevant?
RBCs- 120 days
neutrophils- 7-8 hrs
Platelets- 7-10 days
-if bone marrow suddenly shuts down neutrophils will be the first to drop
what are erythroblasts and myeloblasts?
what are reticulocytes?
name the primitive nucleated precursor for erythroblasts and myeloblasts
-immediate red cell precursor, polychromasia if in increased levels
What are Megakaryocytes?
What are Myelocytes?
- platelet precursor, polyploid
- nucleated precursor between neutrophils and blasts
Name the cell that produces precursor blood cells
haemopoetic progenitor cell
Name the cell that produces progenitor cells?
haemopoitic stem cells
Give the sites of haemopoiesis at each stage of development:
- Where are all haemopoitic stem cells derived from?
- wk 5- wk 10
- wk 6
- week 12
- wk 16
- adulthood
- mesoderm
- yolk sac
- liver
- spleen (small contribution)
- bone marrow
- axial skeleton- vertebra/sternum/ribs
where are bone marrow biopsies collected in:
- children?
- adults?
- shaft of the tibia
- illiac crest or sternum
OR can mobilise stem cells from the marrow into blood for collection and transplantation
give the 3 different compartments in the bone marrow?
- where is the most haemopoetic activity?
- what is the endosteum?
cellular
(haemopoietic cells and non haemopoitic cells)
Vascular elements
connective tissue matrix
- trabecular bone, found throughout the metaphysis such that many cells in this region are close to the bone surface
- the interface between bone and bone marrow, covered by bone lining cells
- what are sinusoids?
- what is their function?
- describe the vascular relationship of the sinusoids?
specialised venues that form a reticular network of fenestrated vessels
- to regulate the passage of cells in and out of the circulation
- arteries feed into the sinusoids
what do reticular cells do in th bone marrow?
contains smooth muscle and can contract and regulate opening of holes between endothelial cells and the BM
- how do mature cells enter the circulation?
- how do different cell types travel to the sinusoid?
-can pass through fenestrations in endothelial cells to enter circulation
-neutrophils actively migrate towards the sinusoid
Megakaryocytes extend long branches called pro platelets into the sinusoidal vessels
RBC release assoc with sinusoidal dilatation and inc blood flow
- what is the difference between red bone marrow and yellow bone marrow?
- what happens within the bone marrow with age?
Red- haemopoietically active
yellow- fatty, inactive marrow
there is a reduction in marrow cellularity with age
what is the myeloid:erythroid ratio?
-how might it change in haemolysis?
the relationship of neutrophils and precursors to proportion of nucleated red cell precursors (from 1.5:1 to 3.3:1)
-see an increase in erythroid activity and the ratio reverses
haemopoiesis regulation -how is haemopoiesis regulated? -what regulates neutrophil maturation? -what regulates the growth of megakaryocytic from their precursors -
interplay of random intrinsic properties of cells (stem cells) nd signals from immediate surroundings and the periphery
+ activation of lineage specific transcription factors
- G-CSF
- Thrombopoietin
why are cells located in different places within the bone marrow?
what is are the 2 clinical indications fro this?
the haemopoitic niche exists for the haemopoitic stem cell
- Niche can shift in states of marrow stress
- drug can be used to mobilise HSC from niche for collection and transplantation
How do you asses haemopoiesis?
blood count
cell indices
morphology
less commonly: bone marrow examination
how might you asses precursor cells?
-how does this work?
expression of antigens indicating lineage or take of development can be studied in /on cells = Immunophenotyping
-identify patterns of antigen expression unique to cell lineage and use antibodies specific to different antigens
How are donated stem cells collected?
- what is the issue with this method?
- how is it resolved?
- collected due to specific gravity
- the specific gravity and morphology is fairly similar in all WBCs
- Use antibodies with fluorescent markers to distinguish between CD3/CD34 then use flow cytometry to determine the volume of stem cells gathered
