haematopoiesis Flashcards
what is haematopoiesis
the formation and development of blood cells
where do cells come from?
- bone marrow
- either red (developing) or yellow (fat)
secreted signal process
- cell receives external signal
- initiates signal cascade
- signal transduction to nucleus results in activation of transcription factors
- cell starts to produce new cell surface receptors - promoting differentiation
stages of cell development
- haematopoietic stem cells
- common progenitors
- committed progenitors
- mature cells
colony stimulation factors (CSF)
determine which major branch a cell will differentiate to
what do growth factors do?
influence different stage depending on where there are acting
what functions are affected by CSF
- haematopoietic
- common progenitors
- committed progenitors
- mature cells
how does CSF affect haematopoietic function
- changes frequency of stem cell division
- changes probability of stem cell death
- probability that daughter cells will become committed progenitors
how does CSF affect common progenitors
- division cell type of committed progenitors
- probability of progenitors death
how does CSF affect committed progenitors
number of divisions before terminal differentiation
how does CSF affect mature cells
lifetime of cell differentiated cells
what do stem cell factors do
- maintain haematopoietic stem cells
- promote survival and proliferation
- interleukins determine differentiation
what do interleukins do
they determine which branch of the cell will differentiate
megakaryocytes
creates platelets
- have multiple nuclei
erythrocytes
- high levels of erythropoietin - high levels means that they are committed and can’t change path
- condensation of nuclei makes reticulocytes (they don’t need to have a nucleus)
- no organelles
regulation of thrombopoiesis
- production of platelets is regulated by their own level on the blood stream
- platelets bind to thrombopoietin (self-regulating on how many platelets are produces)
- quick responsive negative feedback
where is thrombopoietin produced
produced by the liver and kindey
what does thrombopoietin do
signals the bone marrow to increase platelet production
development of erythrocytes
- stem cells
- proerythroblast
- basophilic erythroblast
- polychromatic erythroblast
- orthochromatic erythroblast
- reticulocyte
- erythrocytes
proerythroblast
- large
- small cytoplasm
- lots of RNA and ribosomes
- no haemoglobin
basophilic erythroblast
- some condensation and clumping of chromatin
- cells start to shrink
polychromatic erythroblast
- increasing cytoplasmic haemoglobin
- nucellar chromatin
- even more condensation
- no more division
orthochromatic erythroblast
- rich in haemoglobin
- some ribosomes
- degenerating cytoplasmic organells
reticulocytes
- nucleus expelled
- mitochondria ribosomes and Golgi to make haemoglobin
