Session 6 - Haemopoesis, the spleen and bone marrow Flashcards
Understand and explain the basics of haemopoiesis:
What is haemopoiesis?
Haemopoiesis is the process by which blood cells are formed.
It involves specification of blood cell lineages, and proliferation, to maintain an adequate number of cells in the circulation
Where does haemopoiesis occur before and after birth?
- Early embryo –process begins in the vasculature of the yolk sac before shifting to the embryonic liver by ~week 5-8 gestation
- After birth–sole site of haemopoiesis is in bone marrow
Understand and explain the basics of haemopoiesis:
What is haemopoiesis driven by?
Haemopoetic stem cells
Describe where the production of blood cells occurs in adults and infants
- In adults = limited distribution (pelvis, sternum, skull, ribs, vertebrae)
- In infant = extensive throughout skeleton
Name the 5 major lineage pathways that arise from haemopoetic stem cells
- Thrombopoiesis
- Erythropoeisis
- Granulopoeisis
- Monocytopoeisis
- Lymphopoeisis
What determines the differentiation of haemopoeitic stem cells into different lineages?
- Hormones
- Transcription factors
- Interactions with non-haemopoetic cell types (e.g. endothelial cells)
Describe the pathways that lead to the production of different blood types
Name 2 important hormones in haemopoeisis
1) Erythropoietin
2) Thrombopoietin
What is Erythropoietin secreted by and what does it do?
- Secreted by kidney
- Stimulates red blood cell production
What is Thrombopoietin secreted by and what does it do?
- Produced by liver and kidney
- Regulates production of platelets
Describe the process of thrombopoiesis
-Thrombopoiesis results in the ultimate formation of platelets involved in clot formation
- Platelets have no nuclei and are membrane bound fragments of cytoplasm that bud off from megakaryocytes
What is another name for platelets?
Thrombocytes
Describe the process of granulopoiesis
Granulopoiesis is the process by whichgranulocytes arise from myeloblast cells which in turn arise from common myeloid progenitor cells
Identify the three granulocytes
Describe the process of monocytopoiesis
Monocytopoiesisis the process which leads to the production of monocytes (andsubsequently, macrophages)
What do monocytes do?
Monocytes circulate in the blood for ~1-3 days before moving into tissues where they differentiate into macrophages or dendritic cells
Describe the process of lymphopoiesis
Lymphopoiesisis the process in which lymphocytes develop from a common lymphoid progenitor cell
Identify some lymphocytes
- B cells
- T cells
- Natural killer cells
Describe the process of erythropoiesis
Erythropoiesis is the process by which red blood cells are produced from a common myeloid progenitor cell in the bone marrow
What is another name for red blood cells?
Erythrocytes
Describe the function of erythrocytes (6)
- Transports oxygen to tissues around the body and transports CO2 to your lungs for you to exhale