Haematopoiesis Flashcards
What is haematopoiesis and where does it occur?
The process by which blood cells are produced
RBCs and granulocytes mostly produced in red
bone marrow
Agranulocytes mostly produced in spleen,
thymus and lymph node
(two branches of WBC’s)
Name the 2 Agranulocytes and 3 Granulocytes?
Agranulocytes: Monocytes and Lymphocytes
Granulocytes: Neutrophils, Eosinophils and Basophils.
What are the Sites of blood cell production at different stages of development?
Foetus
Mesoblasticphase: Yolk sac
Hepatic phase:(3-6 month) Liver, with contribution from spleen, lymph nodes and thymus.
Myeloid phase:(6thmonth +) red bone marrow
Adolescent
Marrow of sternum, ribs, skull, vertebrae, pelvis,femur and tibia
Adult
Marrow of sternum,ribs, skull, vertebrae and pelvis
Extramedullar
During abnormalcircumstances, e.g. destruction of red bone marrow. Liver and spleen
Where is red bone marrow found.
In spongey bone within the ends of long bones, the pelvis, ribs, skull bones and vertebrae.
Why is red bone marrow so vascular and how does this aid in its function?
To enable RBC’s to enter the blood and for nutrient delivery which allows it to efficiently produce RBS’s, WBC’s and platelets and enter the blood easily.
Outline the development of a multipoint stem cell into various other cells?
They develop into Myeloid progenitors and Lymphoid progenitors.
Myeloid progenitors develop into megakaryocytes, erythroblasts and myoblasts. (all except lymphocytes)
Lymphoid progenitors develop into different kinds of lymphocytes.
Name the three types of cytokines involved in haematopoiesis, their origin and influence on growth/differentiation.
Erythropoietin:
Kidney cells
Influence growth of RBC’s
Thrombopoietin:
Liver
Influence megakaryocytes
Colony stimulating factors, Interleukins, Stem cell factors:
Endothelium, Fibroblasts of bone marrow and Leukocytes
All types of blood cells
Why is it important for Leukocytes to produce Cytokines?
To aid in fighting infection.
Which white blood cells are involved in cytotoxicity, phagocytosis and antibody formation?
Cytotoxic: Lymphocytes and Eosinophils
Antigen presenting: Eosinophils, Monocytes and Lymphocytes
Phagocytes: Monocytes, Eosinophils and neutrophils
Outline the negative feedback loop that leads to erythropoiesis:
Hypoxia
Reduced oxygen in blood
Kidney secretes erythropoietin
erythropoietin stimulates red bone marrow
Red blood cells develop from stem cells
Increased oxygen carrying ability of blood
Outline the process of erythropoiesis?
Stem cells develop into erythroblasts
Erythrocytes develop into reticulocytes which are secreted
Reticulocytes develop into RBC’s in the blood
Where is erythropoietin secreted and inactivated and how long does it last.
Liver and Kidney(most) in adults
liver in foetus
inactivation in liver
increases RBC production for 2-3 days and 5h half life
What is recombinant erythropoietin and what is it used for ?
EPO made in lab used for the treatment of renal failure, autologous transfusions and blood doping (more oxygen to muscles delay fatigue)
How many RBC’s are produced from 1 stem cell.
16
At what stage do RBC’s lose their organelles and shrink
Normocytes/erythroblasts
How does anemia lead to an increase in reticulocytes?
decreased oxygen in blood
increased EPO production in kidneys
increased amount of reticulocytes released into blood
What two substances does erythropoiesis depend on?
vitamin B12 and folic acid
What does too much folic acid lead to ?
megaloblastic anemia
Outline the path vitamin B12 follows and why it is not secreted by the kidneys.
Bonds to intrinsic factors in stomach
Unbinds in Ileum
Released into blood
Binds to transcobalamin in blood which is not filtered by kidneys as it is a protein.
