Haemopoiesis Flashcards
What size should RBC be?
The same size as a neutrophils nucleus or the same size as a small lymphocyte
Which cells are granulocytes?
Neutrophil, basophil and eosinophil
Describe haematopoietic stem cells
All blood cells come from these, they reside in small numbers in the bone marrow (10^4). 1 in every 20 million nucleated cells in bone marrow is a HSC
What is meant by totipotent?
The cell can form all cells in embryo
What is a pluripotent and multipotent cell?
Can develop into many different cells such as RBC, WBC, muscle, nerve and bone, but after maturation, the cell loses the ability to self-renew
Describe a stem cell
Not terminally differentiated, can divide without limit. Division results in daughter cell having choice, which depends on environmental cues
What does it suggest if there are blast cells in the peripheral blood?
Suggests acute leukaemia or malignancy
what are the major sites in the body of haemopoiesis?
Femur, sternum and pelvis, minor sites include the ribs
What are the sites of haemopoiesis at different ages?
Between 0-2 months it takes place in the yolk sac, from 2-7 months liver and spleen take over. From 5-9 months it occurs in the bone marrow
What is extramedullary haemopoiesis?
Liver and spleen have the ability to resume haemopoietic activity
How is haemopoiesis controlled?
Can be extrinsic and intrinsic. Extrinsic controls it via cell to cell interaction as well as environmental factors such as cytokines. Intrinsic controls via genetic events such as transcription factors
What is a normoblast?
A premature RBC that is committed, seen in the marrow, but should not be seen in peripheral blood. It forms into reticulocyte when it loses its DNA. Should see approximately 1-2% in blood, higher suggests problem such as haemolytic anaemia, less suggests problem in bone marrow
What is EPO?
Essential erythroid growth factor that is made in the kidneys by HIF-alpha and beta under hypoxic conditions.
How does EPO initiate haemopoiesis?
On the surface of the HSC there are EPO receptors, that EPO will bind to and change its shape. Once its shape has changed it attracts JAK, which then phosphorylates itself and causes phosphorylation of STAT, which will go to the nucleus as a transcription factor
What are neutrophilia and neutropenia?
Neutrophilia - Increased neutrophils in the blood. Increases in response to bacterial infections, inflammatory diseases, steroid medication or more rarely leukaemia
Neutropenia - Decreased neutrophils in the blood. Maybe the result of a severe infection or other conditions such as responses to various medications or chemotherapy
