Normal Erythropoiesis Flashcards
What are the properties of red blood cells?
Full of haemoglobin to carry oxygen
No nucleus or mitochondria
High surface area:volume ratio to allow gas exchange
Flexible to squeeze through capillaries
Why do red blood cells have no nucleus?
To allow more space for haemoglobin molecules and to make the cell more deformable
What are some issues caused by the adaptions of red blood cells?
High oncotic pressure and oxygen rich environment
Limited lifespan and can’t divide or replace damaged proteins
Can only produce energy by glycolysis
What are some features of the red blood cell membrane?
Complex structure = not just lipid bilayer
Protein spurs and anchors to make it flexible
What is required to allow red blood cells to keep water out?
Energy is needed to maintain specific ion concentrations
What maintains ion concentrations in red blood cells?
The sodium potassium pump = keeps water out but requires ATP
What is haemoglobin?
Tetrameric globular protein
What chains does adult haemoglobin consist of?
2 alpha and 2 beta chains
What does the heme group consist of?
Fe2+ in a flat porphyrin group = oxygen binds to Fe2+
How many heme groups are there per subgroup?
One heme per subgroup = 4 subgroups per haemoglobin molecule so 4O2 can bind
Where does red blood cell production occur?
In the bone marrow = result of HSC proliferation and differentiation
What regulates red blood cell production?
Erythropoietin
When is erythropoietin released by the kidneys?
When hypoxia is sensed by kidneys = releases erythropoietin to stimulate red blood cell production
Where does red blood cell destruction normally occur?
In the spleen
What is the average lifespan of a red blood cell?
120 days
What cells take up aged red blood cells?
Macrophages
What happens when red blood cells are destroyed?
Contents are recycled = globin chains recycled to amino acids
Heme group broken down to iron and bilirubin
What happens to the bilirubin produced by heme breakdown?
Taken to liver and conjugated then excreted in bile
What are the steps in the breakdown of heme?
Heme - porphyrin - biliverdin - bilirubin
What are reactive oxygen species?
Free radicals that have unpaired electrons (e.g hydrogen peroxide)
Why are reactive oxygen species an issue?
They interact with other molecules and damage their structures
What is the importance of glutathione?
Protect against hydrogen peroxide by reacting with it to form water and GSSG
How is glutathione replenished by the body?
Using NADPH
How is NADPH replenished?
Using the hexose monophosphate shunt
