16. Haemopoiesis Flashcards
What is haemopoiesis
production of blood cells and platelets, which occurs in the bone marrow.
What two things can the hemocytoblast/ haemopoietic stem cell differentiate into?
- Common myeloid progenitor
2. Common lymphoid progenitor
What is the difference in differentiating ability of Haemopoietic stem cells and Common progenitors.
- Haemopoietic stem cells have the ability to self replicate and differentiate further
- Common progenitors only have the ability to differentiate into lineage bound
Will the cells found in the bone marrow end up in blood and if not what happens to them?
- Not all cells found in the bone marrow will end up in the blood
- Some will undergo programmed cell death (apoptosis)
Give 4 features of red blood cells ad explain how the features help with their function?
- Biconcave shape to increase surface area for diffusion of gases
- No nucleus/minimal organelles to maximise oxygen holding capabilities
- No mitochondria to ensure oxygen is not used up by erythrocyte
- Haemoglobin to increase affinity of oxygen binding (made from iron)
What is Erythropoiesis?
process which produces red blood cells, which is the development from erythropoietic stem cell to mature red blood cell.
Describe the process of Erythropoiesis
- Erythroblasts (immature blood cell) start of with large nucleus, prominent nucleoli and large amounts of RNA
- Gradually nucleus shrinks and is removed along with majority of RNA
- forms RETICULOCYTES - The final step before a mature erythrocyte -once the nucleus has been removed
- Only a small amount of RNA remains to help make haemaglobin
- This is removed in 1-2 days
What happens during blood loss?
- The kidney senses tissue hypoxia
- The kidney increases secretion of erythropoietin - a hormone
- Erythropoietin is a glycoprotein produced by the kidney to increase levels of red blood cells
- Acts to stop programmed cell death (apoptosis) of erythrocyte progenitors
What is Granulopoiesis?
production of granulocytes from myeloblast
What are the 3 granulocytes?
Basophils, neutrophil, eosinophil
Why are granulocytes so called?
due to the presence of granules within their cytoplasm
What is the function of granulocytes?
All act to mediate inflammatory reactions in the body
• All act by releasing cytokines, interleukins, leukotrienes
What happens during Granulopoiesis?
All 3 lineages go through the process of:
• Nuclear condensation and lobulation
• Formation/increased numbers of granules
Give two features of Neutrophils
Multilobed nucleus
• 3 types of granules
What is the function of neutrophils?
Kill pathogens by:
• Phagocytosis
• act as the middle person i.e signalling and antigen presentation
• Neutrophil Extracellular traps (NETS)
• Respiratory burst - rapid release of reactive oxygen species (superoxide radical and hydrogen peroxide) - to degrade internalized particles and bacteria.
Which hormone stimulates neutrophil production?
COLONY STIMULATING FACTOR (G-CSF)
What secretes the G-CSF hormone and when are they secreted?
Secreted by multiple immune cells in the body and endothelial cells
• Usually released in response to inflammation
What does the G-CSF hormone do?
- Acts on the bone marrow to increase the number of circulating neutrophils
- Increases the speed at which nuetrophils mature as well as the numbers
Five two features of basophils?
- Bilobed nucleus
- Purple granules (stained due to basic dye)
- Granules contain histamine and heparin
What is the role of basophils?
- Release histamine to trigger inflammation
* Mediate hypersensitivy reactions (eg asthma)
Give two features of EOSINOPHILS
- 2 nucleur lobes
* Spheric granules- eosinophilic (acid-loving) granules
What are the roles of eosinophils?
- Phagocytose pathogens
* Fight parasitic worms and have a role in inflammation/allergy
What do the eosinophil granules contain?
- antihelminthic proteins such as major basic protein and eosinophilic cationic protein
- Cell component destroying enzymes (eg phosphlipases and acid hydrolases)
Are monocytes granulocytes And why?
No • Monocytes are agranulocytes - absence of granules in their cytoplasm,
What are monocytes called in tissue?
• Monocyte in the blood- macrophage in the tissue
What are the function of monocytes/macrophages?
- Phagocytose pathogens, cell debris and senescent cells
* Present foreign antigens i.e raise the alarm
What is the shoe of nucleus in monocytes/macrophages?
• Unilobular ”horseshoe” shaped nucleus
What is thrombopoiesis?
• Thrombopoiesis is the production of thrombocytes (platelets) from megakaryocytes
Which hormone controls production of thrombocytes And where is it produced?
thrombopoietin from the liver
What is the function of platelets?
Function to stop bleeding and mediate haemostasis
Give 3 features of platelets(thrombocytes)?
- Biconvex shape
- No nucleus- just cytoplasm
- contains vast amount of proteins and clotting factors
What is Lymphopoiesis?
Production of lymphocytes
What are the. Types of lymphocytes?
- B Lymphocyte
- T Lymphocyte
- (Natural killer cell)
What is the main function of b lymphocytes?
production of antibodies
Where does maturation of b lymphocytes occur?
in the bone marrow and then in:
• Intestines (peyers patches)
• Spleen
• Lymph nodes
Which immunity are b lmphocytes involved in?
humoral adaptive immunity
What is the main function of t lymphocytes?
Kill virus-infected cells, neoplastic cells and transplanted tissue
• Carry out cell-mediated immunity
• Activate B cells to make antibodies using IL 4
Which hormone is involved in the production lymphocytes?
Interleukins
Describe the structure of t lymphocytes
Large nucleus with small rim of cytoplasm
Where do T cells mature?
- T cells start off in the bone marrow or fetal liver and then will migrate to the thymus to mature
- After this they will migrate to secondary lymhoid organs where they will wait until activation
