Intro to Haematology Flashcards
What are the 3 main types of blood cells?
White blood cells (leucocytes)
Red blood cells (erythrocytes)
Platelets
The main role of red blood cells?
Transporting gases in the bloodstream (oxygen and carbon dioxide)
The main role of white blood cells?
Fighting infection
The main role of platelets?
Preventing bleeding i.e. formation of clots.
What is haematopoiesis and where is a site of occurrance?
The term used for the production of blood cells.
Occurs mainly in the bone marrow
The sites of haematopoiesis vary with age. True/false?
True
What are the various sites of haematopoesis?
Embryo: yolk sac then liver then marrow, 3rd-7th month in spleen.
At birth: mostly bone marrow, liver and spleen when needed.
Adult: haematopoiesis restricted to skull, ribs, sternum, pelvis, proximal ends of femur (axial skeleton).
What happens to the number of active sites for haematopoiesis in the bone marrow from birth to maturity?
The number of active sites in the bone marrow decreases but retain ability for haematopoesis.
What is erythropoiesis?
The production of red blood cells.
What are the phases of erythropoiesis?
Proerythroblast
Basophilic erythroblast (early)
Polychromatophilic erythroblast
Orthrochromic erythroblast
Reticulocyte
Mature RBC
One pronormoblast will result in many mature erythrocytes. True/false?
True
What is thrombopoeisis?
Platelet formation
What are the 3 main types of granulocytes?
Neutrophils, eosinophils and basophils
What granulocyte is found most commonly?
Neutrophils
Why are the cells known as granulocytes?
They contain granules that are easily visible on a stained blood film.
The 3 types are named based on the pattern of uptake of stain.
Eosinophils - the granules take up eosin which is red and acidic.
Basophils - the granules take up basic (alkali) dyes which are densely blue.
Neutrophils - the granules are fine and a “neutral” mix of the two colours.
Characteristics of neutrophils?
Segmented nucleus, neutral-staining granules.
Immediate defence cell - phagocytes, release granule contents (die in process).
Attract other cells
Increased by body stress - infection, trauma, infarction.
Characteristics of eosinophils?
Usually bi-lobed, bright orange/red granules.
Fight parasitic infections
Involved in hypersensitivity, often elevated in patients with allergic conditions e.g. asthma.
Characteristics of basophils?
Large deep purple granules obscuring nucleus.
Quite infrequent in circulation.
Granules contain histamine.
Role is unclear, involved in mediation of hypersensitivity reactions
Features of monocytes?
Large single nucleus, faintly stained granules, often vacuoled.
Circulates for a week and enter tissues to become macrophages.
Phagocytose invadors - kill them, present antigen to lymphocytes.
Attract other cells
Much longer lived than neutrophils
Features of lymphocytes?
Small with condensed nucleus and rim of cytoplasm, when activated they appear large with plentiful blue cystoplasm extending around neighbouring red cells.
Cognate infection response.
What tests are used to recognise the more primitive precursors?
Immunophenotyping
Bioassays
What is immunophenotyping?
An expression profile of proteins (antigens) on the surface of cells.
What are bioassays?
Culture in vitro and show lineage of progeny in different growth conditions.
In clinical practice, how is the haematopoietic system examined?
Look at the peripheral blood (full blood count and blood film)
Look at the bone marrow - posterior iliac crests are common sites for bone marrow aspiration and biopsy
Specialised tests i.e. immunophenotyping and genetic tests).
Look at other sites that are relevant to blood production e.g. splenomegaly, hepatomegaly, lymphadenopathy.
