L9- Haematopoiesis Flashcards
What are the components of the blood system?
Products= RBC’S, Coagulation factors, WBC’s
Production line in bone marrow= Bone marrow, Lymphatic system
What is a telomere?
A repeating sequence of double stranded DNA located at the ends of chromosomes.
What does the length of a telomere show?
Greater telomere length is associated with immortalised cell lines such as cancer and embryonic stem cells.
Telomere lengths progressively shorten as cells divide and differentiate in their lifespan
What is the telomerase enzyme?
Lengthens telomeres by adding on repeating sequences of DNA.
High levels of telomerase activity are detected in embryonic stem cells and cancer cells, whereas little to no activity in mature, differentiated cell types.
What do haematopoietic stem cells differentiate into?
Haematopoietic progenitor cells differentiate into different cell types found within the blood such as erythrocytes, megakaryocytes and leukocytes (lymphocytes, granulocytes, DC’S, monocytes)
What is a niche?
Specialised microenvironment within which stem cells can self renew
Contains stromal mix with growth factors and adhesion sites
Prevents differentiation; promotes self renewal
What happens in a non-niche environment?
Induces stem cell differentiation and division via signals into different cell types instead of self renewal
What is divisional asymmetry?
Cell fate determinants are asymmetrically localised to only one daughter cell which retains stem cell fate while the other differentiates
What is environmental asymmetry?
After division one daughter cell remains in the self renewing niche microenvironment while the other relocates outside the niche to a different, differentiation promoting microenvironment
What does the bone marrow contain?
- Nutrients- iron, protein
- Haemoglobin synthesisi
- Packaging (RBC formation)
What happens in haemoglobin synthesis?
Iron and protoporphyrin produce haem and globin which combine to form haemoglobin
What are microRNA’s?
Key regulators of stem cell differentiation
What inhibits iron?
Iron deficiency due to chronic inflammation or malignancy
What inhibits protoporphyrin?
Anaemia
What inhibits globin packaging?
Thassalaemia
