Erythropoesis Flashcards
(28 cards)
What are the features of RBCs?
full of Hb to carry blood
no nucleus or mitochondria
high surface area:volume ratio - allows gas exchange
flexible
What are the downsides to RBCs specialised features?
oxygen carries oxidation risk
Hb = high oncotic pressure
no nucleus so cant replace damaged proteins
no mitochondria to relys on glycolysis for energy generation
How does the RBC membrane keep the ion concentration correct?
Na/K pump
What is the structure of Hb?
tetrameric
per subgroup: 1 heme and 1 Fe 2+ iron
What is the composition of adult Hb (HbA)?
2 alpha 2 beta
What is the composition of foetal Hb (Hbf)?
2 alpha 2 gamma
What state must iron be in to carry oxygen?
Fe2+
Whats the function of Hb?
deliver oxygen to tissues when pO2 is too low
act as a buffer for H
CO2 transport
What type of binding do O2 and Hb exhibit?
allosteric - once O2 binds it makes it easier for the other 3 Hb units to bind O2
What type of curve does Hb and O2 binding show?
sigmoidal curve
What mediates eryhropoesis?
EPO - erythropoitin
What triggers EPO release?
hypoxia - sensed by the hypoxia center in the kidneys
What produced EPO?
kidneys
What is required for erythropoesis?
B12, folate, iron, EPO
What is the average RBC lifespan?
120 days
Where are RBCs destroyed?
liver and spleen
What are globin chains broken down into?
amino acids
What is heme broken down into?
iron and bilirubin which is taken to the liver and conjugated then excreted in bile
What do free radicals do to Fe2+?
oxidise it to Fe3+ which does not transport oxygen
Name two reactive oxygen species/free radicals?
superoxide and hydrogen peroxide
How do reacive oxygen species cause damage?
they have unpaired electrons so damage molecules
How are free radicals prevented from damaging oxygen?
Glutathione reacts with hydrogen peroxide to form water and GSSG
What replenished Glutathione?
NADH
How is NADH generated?
hexose monophosphate shunt
