Week 2- haemopoeisis Flashcards
What is haemopoeisis?
The production of blood cells.
What are all the mature blood cells called?
Erythrocytes
Platelets
White blood cells- Neutrophils Eosinophils Basophils Granulocytes Monocytes- macrophages Lymphocytes- B cells, T cell and NK cells.
What is myelopoeisis?
Production of granulocytes and monocytes within the bone marrow (also known as granulopoeisis).
What is thrombopoeisis?
Production of platelets (also known as thrombocytes)
Life span of a RBC?
120 days
Life span of neutrophils
6-8 hours
Life span of platelets
7-10 days
What does the suffix ‘blast’ mean?
Precursor cell
Erythroblast- red precursor cell
Myeloblast-precursor granulocyte.
What is a megakaryocyte?
Platelet precursor.
What are reticulocytes?
Polychromatic immediate red cell precursors (as red cells are released from the marrow- this is what they are).
What are myelocytes?
Nucleated precursors between neutrophils and neutroblasts.
Where do all these precursor cells come from?
Haemopoetic progenitor cells.
Describe the developmental events in haemopoeisis?
Self renewal- a property of stem cells lost in descendants
Proliferation- increase in numbers
Differentiation- descendants commit to one or more lineage
Maturation- descendents acquire functional properties and may stop proliferating
Apoptosis- descendants undergo cell death.
Describe how the location of haemopoeisis changes during development?
Yolk sac- first sight of erythroid activity stops by week 10 Liver- starts by week 6 Spleen- starts by week 12 Bone marrow- starts by week 16. In adults- moves to axial skeleton.
How does the location of haemopoeisis affect how you would withdraw bone marrow biopsies?
In children- use the anterior tibia
In adults- use PSIS.
What non-haemopoetic cells also occupy the bone marrow?
Osteoclasts and osteoblasts
Adipocytes (fat tissue)
Describe the vasculature of the bone marrow?
The nutrient artery supplies it. Arterioles branch into the bone to supply it. The arteries drain into sinus’s which have large pools of blood.
How can mature cells exit the marrow?
Formed blood cells can pass through fenestrations in endothelial cells to enter the circulation.
What is release of red cells associated with (in terms of the sinus’s)?
What do neutrophils do?
What do megakaryocytes do?
Associated with sinusoidal dilatation and increased blood flow.
Neutrophils actively migrate towards the sinusoid.
Megakaryocytes extend long branching processes into the sinusoid blood vessels.
What does having red marrow mean?
Its haemopoetically active
What does having yellow marrow mean?
Its fatty and inactive.
How does the marrow change as we get older? (in terms of yellow and red)
You get an increase in yellow marrow with age meaning you get a reduction in marrow cellularity.
What is the myeloid: erythroid relationship?
Relationship of neutrophils and its precursors to the number of red cell precursors.
What two things can regulate haemopoeisis?
Intrinsic properties of cells (stem cells vs progenitor cells vs mature cells)
Signals from immediate surroundings and the peripheries.
