Physiology - Haematopoiesis Flashcards
What are the three main types of blood cells?
Red blood cells
White blood cells
Platelets
What is the term for the production of blood cells?
Haematopoiesis
Where does haematopoiesis occur in the embryo?
Yolk sac, then liver, then marrow
3rd to 7th month –> spleen
Where does haematopoiesis occur at birth?
Mostly bone marrow
Liver + spleen when needed
Where does haematopoiesis occur in adults?
Bone marrow only:
- skull, ribs, sternum, pelvis + proximal femur (axial skeleton)
- not all bones contain bone marrow
From which type of cell are all blood cells derived?
Haematopoietic stem cells
What are the different types of white blood cells?
Granulocytes: - neutrophils - eosinophils - basophils Monocytes: - macrophages Lymphocytes: - B cells - T cells - NK cells
What are neutrophils responsible for?
Phagocytosis/acute inflammation
What are eosinophils responsible for?
Destroy parasites
Modulate hypersensitivity reactions
What are basophils for?
Modulate hypersensitivity reactions
Circulating version of tissue mast cell
What are macrophages responsible for?
Modulate immune reactions
Phagocytic clearance
Regulatory functions
What are B cells responsible for?
Humoral immunity (antibodies)
What are T cells responsible for?
Cell-mediated immunity
Regulatory functions
What are NK cells responsible for?
Anti-viral/tumour
What is the lifespan of a red blood cell?
about 120 days
What is the lifespan of a neutrophil?
7-8 hours
What is the lifespan of a platelet?
7-10 days
What do ‘blasts’ refer to in haematopoiesis?
Nucleated precursor cells e.g. erythroblast, myeloblast
What is the platelet precursor cell called?
Megakaryocyte
What is the immediate red cell precursor called?
Reticulocyte (immature RBC)
What does a neutrophil look like under a microscope?
Segmented nucleus (polymorph) Neutral staining granules
What do eosinophils look like under a microscope?
Usually bi-lobed
Bright orange/red granules
What do basophils look like under a miscroscope?
Infrequent in circulation
Large deep purple granules obscuring nucleus
What do monocytes look like under a microscope?
Large single nucleus
Faintly staining granules, often vacuolated
What do lymphocytes look like under a microscope?
Mature: small with condensed nucleus + rim of cytoplasm
Activated (often called atypical): large with plentiful blue cytoplasm extending around neighbouring red cells on the film, nucleus more ‘open’ structure
Which investigations can be done to identify the more primitive precursor cells?
Immunophenotyping
- expression profile of proteins (antigens) on surface of cells
Bio-assays
- culture in vitro and show lineage of progeny in different growth conditions
(cant be identified on blood films)
How do you examine the haematopoietic system?
Peripheral blood: blood count, cell indices, morphology
Look at bone marrow
Specialised tests of bone marrow
Other sights relevant to blood production e.g. splenomegaly, hepatomegaly, lymphadenopathy
What is the most common site for bone marrow aspiration/biopsy?
Posterior iliac crests
What is the difference betweek red and yellow marrow?
Red = haemopoietically active Yellow = fatty, inactive
What is the myeloid:erythroid ratio?
Ratio of neutrophil + precursors to nucleated red cell precursors
What is the most appropriate technique to assign cell lineage?
Immunophenotyping
