Haematopoiesis Flashcards
What is haematopoiesis?
the production and development of blood cells
Describe the haematopoiesis differentiation pathway?
pluripotent blood stem cell –> myeloid stem cell – RBCs, platelets, myeloblast. Myeloblast –> granulocytes (eosinophil, basophil, neutrophil)
pluripotent blood stem cell –> Lymphoid SC –> Lymphoblast –> B and T lymphocyte and NK cell.
granulocytes, B, T and NK = WBCs
Where does adult haematopoiesis occur?
axial skeleton (sternum, vertebra, ribs, pelvis, proximal long bones, skull)
Where does foetal haematopoiesis occur?
yolk sac, liver, spleen, lymph nodes
Where does babies and children haematopoiesis occur?
all bone marrow
What are platlets?
small particles of cytoplasm budded off megakaryocyte cell. Megakaryocyte stays in bone marrow (not circulation)
How long does it take from pluripotent stem cell to blood element?
2-3 weeks
Difference between symmetric and asymmetric division?
symmetric - x1 multipotent adult stem cell, x2 mature somatic cell differentiated
asymmetric - x2 multipotent adult stem cell, x1 mature somatic cell
What is the average blood volume?
5L
What hormone stimulates RBC proudction?
Erythropoetin (epo) in kidneys
What hormone increases platelet count?
Thrombopoetin (tpo) from liver and kidney, acts on megakaryocytes
What factor increases neutrophils?
GCSF (granulocyte colony stimulating factor) by endothelium. initiates myeloid cells into granulocytes into neutrophils
What increases WBCs?
ILs and cytokines
Describe feedback loop of RBC production and Epo?
Low O2 = liver and kidney ↑ epo = ↑ RBC = ↑ O2 carrying capacity = ↓ epo
Two reasons for high blood counts?
Primary = abnormal bone marrow (malignancy), overproduction
Secondary = normal bone marrow with external factor causing overproduction
Primary and secondary causes of leucocytosis?
P = leukaemia/lymphoma/myeloproliferative disorders
S = infection/inflammation/infarction/tumour
Primary and secondary causes of thrombocytosis?
P = thrombocythemia (treat bone marrow)
S=infection/inflammation/infarction/tumour
What is haematocrit?
ratio of RBCs to total blood volume
Primary and secondary causes of erythrocytosis?
P = polycythaemia vera
S = raised epo levels (low O2, tumours, doping, high affinity Hb)
What the common treatment for a primary cause of increased blood cell number?
P = malignancy = hydroxycarbamide plus aspirin
Two main reasons for low blood count?
underproduction or reduced survival in circulation
Reasons for reduced white cells?
Underproduction = drugs affecting stem cell/part of pancytopenia due to marrow failure
Reduced survival = autoimmune/drugs/viruses
Reasons for reduced platlets?
Underproduction = drugs affecting stem cell/ liver failure (tpo underproduction)/part of pancytopenia due to marrow failure
Reduced survival = autoimmune (ITP)/drugs/hyperslenism/infectoin/inflammation/sepsis
Name 3 drugs that can cause reduced platelets?
penicillin, NSAIDs and furosemide
8 causes of low blood counts by reduced production? (3M,2L,A,H)
Myeloma
Myelodysplasia
Metastatic malignancy
Myelofibrosis
Leukaemia
Lymphoma
Aplastic anaemia
Haematinic deficiency
Name the myeloid white cell malginancies?
Immature cells = acute myeloid leukaemia (AML)
mature cells = myelodysplasia and the myeloproliferative disorders (polycythaemia vera/ chronic myeloid leukaemia/ essential thrombocythemia/myelofibrosis)
Name the lymphoid white cell malignancies?
immature cell = acute lymphoblastic leukaemia (ALL)
mature = chronic lymphocytic leukaemia/
myeloma/ lymphoma.
Describe myelodysplasia (MDS)
abnormal maturation and proliferation of cells in bone marrow (don’t get into blood)
affects red cells, granulocytes and platelets
20% evolve into AML
what is aplastic anaemia?
bone marrow is empty, damage to multi or pluripotent stem cells
reduced erythropoiesis, granulopoiesis and thrombopoiesis
drugs (chemo) / viruses (Hep, EBV, CMV, parvovirus, HIV)/ radiation/ autoimmune
Describe myelofibrosis
malignant reticulin fibre proliferation in bone marrow
anaemia/a leucoerythroblastic blood film/splenomegaly
can develop from MPN
can transform to AML
