Blood Components & Cell Lineage Flashcards
Blood vs plasma vs serum
- Blood - cellular components + plasma
- Plasma - liquid component, including coagulation factors
- Serum - plasma (liquid component) minus coagulation factors
What is the process that produces blood cells
Haematopoiesis
Where does haematopoiesis occur and how does this change with age
- Embryo (0-3 months) - yolk sac then liver
- Embryo (3-7 months) - marrow + spleen
- At birth - mainly marrow (+ liver & spleen when required)
- With growth - only active marrow in axial skeleton, pelvis & proximal long bones
What is the first cell in the blood cell lineage
Haematopoietic stem cells
What processes do stem cells carry out? What state are most stem cells found in?
- Proliferation
- Differentiation (into specialised cells)
- Self renewal
- Most stem cells sit in a quiescent state (reversible non-dividing state)
Describe the haematopoietic tree/ lineage
Haematopoietic stem cells (HSCs) =>
Multi-potent progenitors (MPPs) =>
Common myeloid progenitor (CMP) & Common Lymphoid progenitor (CLP)
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Common myeloid progenitor (CMP) =>
Megakaryocyte-erythroid progenitor (MEP) & Granulocyte-monocyte progenitor (GMP)
MEPs => RBCs & platelets
GMPs => Granulocytes & macrophages
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Common Lymphoid progenitor (CLP) =>
Dendritic cells, T-cells, NK-cells, B-cells
What are granulocytes? What are the three main types?
Granulocytes - WBCs that contain granules that are easily visible on stained blood film
Eosinophils - Take up eosin stain (red & acidic)
Basophils - Take up basic stains (densely blue)
Neutrophils - ‘Neutral’ mix of two colours
Describe the structure of neutrophils
- Segmented, ‘polymorphic’ nucleus
- Neutral staining fine granules
What is the main function of neutrophils? When may they increase in numbers?
- Phagocytosis & granule release (break down tissue & attract cells)
- Increase with bacterial infections, trauma, infarction etc
Describe the structure of eosinophils
- Usually Bilobed
- Acidic (orange/ red) granules
- ‘tomatoes with sunglasses’
When might eosinophil count be high?
- Parasitic infections, allergic reactions & conditions e.g. asthma
Describe the structure of basophils
- Large, deep blue/purple granules
- Granules often obscure the nucleus
Name some examples of molecules that are contained within basophil granules
histamine & heparin
Describe the function of basophils
Function similar to mast cells, help mediate histamine release in IgE hypersensitivity reactions
Describe the structure of monocytes/macrophages
- Large single nucleus
- Faint granules
- Light blue cytoplasm, often with vacuoles
What is the difference between a monocyte & macrophages?
Monocytes - circulate blood for ~week
Macrophages - specialised monocytes that are active in tissues.
Macrophage function
Macrophages are phagocytes and they are important in
- clearing debris,
- removing infective organisms
- presenting antigens to immune cells
- releasing signals to attract other cells
Describe the structure of a mature vs activated lymphocyte
Mature lymphocyte - small, condensed nucleus, little cytoplasm
Activated lymphocyte - large cells, less condensed nucleus, big blue cytoplasm
What feature can be used to help differentiate between a macrophage & activated lymphocyte
Activated lymphocytes often extend up to neighbouring RBCs on blood films
What test can be used to differentiate between types of
A) haematopoietic stem cells
B) blood cell progeny (RBCs, neutrophils etc)
A) HSCs - immunophenotyping
B) Progeny - morphology on blood films
Briefly describe tests used in haematological studies
FBC & blood films (to look at peripheral blood components)
Marrow biopsy (to look at bone marrow)
Special tests such as genetic testing & immunophenotyping
Spleen, liver & lymph node examination (blood production)
Where is a bone marrow biopsy usually taken from
Posterior iliac crest
Bone marrow aspirate vs bone marrow trephine/ column biopsy; What is the use of each?
Cellular aspirate - Can study cellular detail at higher magnitude
Trephine/ column biopsy - ‘Architectural map’ of cells in situ
