Haemopoiesis Flashcards
What is the normal range of RBCs?
3-5 x 10^12/L
What is the normal range of WBCs?
2-6 x 10^9/L
What is the normal range of platelets?
150-400 x 10^9/L
What is the normal lifespan of RBCs?
120 days
What is the normal lifespan of WBCs?
3-5 days
What is the normal lifespan of platelets?
10 days
How does the site of haemopoiesis change over the lifespan?
1st few weeks: yolk sac
6 weeks - 7 months: liver and spleen
7 months - throughout life: bone marrow (axial skeleton and long bones initially, then just axial)
When are the liver and spleen used for haemopoiesis besides in the 6 week - 7 month period?
In childhood or adult pathology of the bone marrow
What % of bone marrow consists of fat spaces? In what areas?
50%
In all marrow, even in active haemopoietic areas
What are the main sites of haemopoiesis in an adult (aged >40-50)?
Pelvis
Sternum
Spine
Maybe some ribs
What is the pluripotent stem cell and what is its role in haemopoiesis?
A cell capable of self renewal that differentiates into all haemopoietic cell lines (as well as osteoclasts)
In what kind of numbers do pluripotent stem cells exist in the marrow?
Small numbers (1 in 100,000 in mice studies)
What is a CFU? Can this be distinguished using microscopy?
Colony-forming unit
No - appear no different histologically but behave in a characteristic way
What is the role of the bone marrow stroma?
Provides a specific supportive microenvironment for bone marrow to grow
Ensures immature cells are not released into the peripheral blood
How are immature cells kept in the bone marrow?
Attached via various adhesion molecules to the bone marrow stroma (ECM and cells)
Changes in adhesion molecules mark the progression of cells through the stroma
Is the bone marrow separate from or in continuity with the systemic circulation?
In continuity with
How is a bone marrow transplant administered?
Via a central line (finds the microenvironment of the stroma and settles in, anchoring to adhesion molecules)
List 5 elements of the bone marrow ECM
Fibronectin Haemonectin Laminin Collagen Proteoglycans
List 5 cells of the bone marrow stroma
Macrophages Fibroblasts Endothelial cells Fat cells Reticulum cells
When can individual cell types and stages of maturation be accurately determined under the microscope?
Beyond the CFU stage
What are haemopoietic growth factors? Are they specific to single lineages or can they work across several?
Glycoprotein hormones which act locally and via the circulation to direct haemopoiesis; effects are mediated through specific receptors
May act specifically on 1 lineage or work across lineages (may also stimulate self renewal, e.g. SC factor for the HSC)
What is the effect of GM-CSF on an early cell vs. a late cell?
Early cell: promotes proliferation/maturation
Late cell: promotes activation to enhance phagocytosis, killing and secretion
Give 3 examples of haematinics
Iron
Vitamin B12
Folate
What is required for functional Hb?
Functional a chain
Functional B chain
Iron
What is the role of iron in RBC function?
Critical to maintain production
What are 2 possible causes of iron deficiency?
Inadequate diet
Blood loss
In what foods is vitamin B12 found? Where is it not found?
Animal products (meat, fish, dairy) Not in fruits, cereals or vegetables
What is the role of vitamin B12 in RBC function?
Important for all rapidly produced cells
In what foods is folate found?
Green leafy vegetables
Give an example of a drug which can cause folate deficiency
Methotrexate
