Haematopoiesis Flashcards
Haematopoiesis
Production of blood cell in an appropriate number, with the ability to adapt to requirements and respond rapidly/effectively
Erythrocyte
RBC
Leukocyte
WBC
Thrombocytes
Platelets
Hematopoietic stem cell
Multipotent stem cell responsible for all blood cell.
Briefly describe myeloid lineage
Hematopoietic cell to myeloid progenitor to either megakaryocyte (platelets), erythrocyte, mast cell and myeloblast (basophil, eosinophil, neutrophil, monocyte –> macrophage. )
Briefly describe lymphoid lineage
Hematopoietic cell to lymphoid progenitor to either natural killer cells or small lymphocytes (T and B cells)
What are granulocytes?
Eosinophils, neutrophils, basophils. Have granules that can directly kill invading organisms.
RBC life span
120 days (35 shelf life span)
WBC life span
5-10 days
Name three cytokines needed for haematopoiesis?
Erythropoietin= increases RBC production G-CSF= increases WBC neutrophil Thrombopoietin= increase platelet.
How are RBC increased?
Erythropoietin is secreted when oxygen level goes down. O2 level detected in kidney. EPO acts on precursors to enhance survival and increase maturation rate. (Can be artificially injected).
How are neutrophils increased?
Neutrophils has natural baseline. Infection causes G-CSF to be secreted from endothelial cells. Increases survival and maturation acts on granulocyte precursor.
How are platelets increased?
Thrombopoietin (TPO) produced in kidney and liver produced constantly but increases in inflammation. Acts on megakaryocytes..
How is TPO stopped?
Negative feedback, platelets destroy TPO.
Describe long term control of blood production
Stem cells can either self renew or differentiate into a lineage.
What prevents haematopoietic stem cell from proliferating into cancer
There aren’t many stem cells, cell division is low, and division is highly controlled. But enough blood cells are still made as 20 generation are made. So 1 stem cell makes 500,000.
Stem cell niche
A niche of proteins and cells that the stem cells require to survive. Die without the niche.
How many cell divisions in haematopoiesis result in cell death?
40%
Whats the point of cell deaths
Naturally occurring cell deaths mean that by stopping cell death the number of cells can increase quickly. Cytokines control the cell lineage
