Flashcards in Introduction to haematology Deck (46)
What is haematopoiesis?
- The physiological developmental process that gives rise to the cellular components of blood
- A single multipotent haemopoietic stem cell can divide and differentiate to form different cell lineages that will populate the blood
What is a haemopoietic stem cell?
- Differentiation potential for all lineages
- High proliferative potential
- Long term activity throughout the lifespan of the individual
- Self renewal
What is symmetric self-renewal?
Increase stem cell pool – NO generation of differentiated progeny
What is asymmetric self-renewal?
Maintain stem cell pool – generation of differentiate progeny.
What is lack of self-renewal?
Deplete stem cell pool – generation of ONLY differentiated progeny
Maintain stem cell pool – NO differentiated progeny
What are the two haemopoietic lineages?
At what point in human development does heamopoiesis start?
Where does heamopoiesis start?
In the aorta-gonado-mesonephros region,
expands rapidly at day 35, then disappear at day 40.
Why does the aorta-gonado-mesonephros region disappear?
This disappearance correlates with the migration of these hematopoietic stem cells to the foetal liver, which becomes the subsequent site of haemopoiesis.
What are the features of erythrocytes?
Bi-concave discs, 7.5 µM diameter
What is the lifespan of an erythrocyte?
What is anaemia?
What is polycythaemia?
Abnormally raised erythrocytes
What is relative polycythaemia?
Plasma volume is reduced so erythrocytes appear raised
What are granulocytes?
Have cytoplasmic granules (neutrophils, eosinophils, basophils)
What is the function of neutrophils?
What is neutrophilia?
Increased numbers of neutrophils
Why might neutrophil levels be increased?
Bacterial infection and inflammation
What is the lifespan of neutrophils?
A few hours
What is neutropenia?
Decreased numbers of neutrophils
Why would eosinophil levels be increased?
- Parasitic infection
Why might basophil levels be increased?
What are monocytes?
- Phagocytic & antigen-presenting cells
- Migrate to tissues & are then identified as “macrophages” or “histiocytes”
e.g. Kupffer cells in liver
e.g. Langerhans cells in skin
What is monocytosis and why might it occur?
Increased numbers of monocytes. Can happen in TB.
What is the function of NK cells?
- Recognise “non-self”
e.g. Cells, viruses
- Large granular lymphocytes
What are B-lymphocytes?
- Adaptive immune system
- rearrange the immunoglobulin genes to enable antigen specific antibody production
- humoral immunity
What are T-lymphocytes?
- Adaptive immune system
- rearrange the T-cell antigen receptor
- cell-mediated immunity
- target specific cytotoxicity
- Interact with B cells, macrophages
- Regulate immune responses
What is lymphocytosis and why might it occur?
Increased numbers of lymphocytes.
e.g. atypical lymphocytes of glandular fever (infectious mononucleosis)
e.g. Chronic lymphocytic leukaemia
What is lymphopenia and why might it occur?
Decreased numbers of lymphocytes.
e.g. post bone marrow transplant