Normal red blood cells Flashcards
Red blood cells don’t have a nucleus or mitochondria, what does this then limit?
No nucleus - can’t divide so limited lifespan No mitochondria - limited to glycolysis for energy generation
Describe the structure of haemoglobin
Tetrameric globular protein, Hb (adult) is 2 alpha and 2 beta chains, haem group Fe2+ in a flat porphyrin ring, one haem per subgroup, one oxygen molecule binds to one Fe2+ (NOT Fe3+), 4 oxygen moleules per Hb
What is the function of haemoglobin?
Deliver oxygen to tissues, act as a buffer for H+, involved in carbon dioxide transport
Where does RBC destruction normally occur?
Spleen
What happens to aged RBCs?
Taken up by macrophages i.e. taken out of the circulation. The contents are then recycled - globin chains recycled to amino acids
What happens to the haem group during RBC destruction?
The haem group is broken down to iron and bilirubin, bilirubin is then taken to the liver and conjugated and then excreted in bile (which colours the urine and faeces)
Name the hormone that regulates RBC production
Erythropoietin
Where is erythropoietin produced?
Kidneys in response to hypoxia
In the glycolysis/Embden-Meyerhof pathway what does NADH do?
Prevents oxidation of Fe2+ to Fe3+
Which molecule protects us from hydrogen peroxide and therefore oxidative damage?
Glutathione (GSH) - reacts with hydrogen peroxide to form water and an oxidised glutathione product (GSSG)
NADPH replenishes levels of GSH (which protects us from hydrogen peroxide i.e. oxidative damage). How is NADPH generated?
By the hexose monophosphate shunt
Name the rate limiting enzyme in the process of glutathione protecting us from hydrogen peroxide
glucose-6-phophate dehydrogenase (G6PD)
How much carbon dioxide is dissolved in solution, bound directly to Hb and transported as bicarbonate respectively?
In solution - 10% Bound to Hb - 30% Transported as bicarbonate - 60%
Oxygen binding to Hb is known as co-operative binding, what does this mean?
As one oxygen binds to a subunit the Hb shape changes. This alters how easy it is for the next oxygen to bind to a different subunit and this changes the shape again i.e. Hb is most attracted to oxygen when 3 out of 4 oxygen molecules are bound to Hb
Out of fetal Hb, myoglobin and normal Hb which saturates the most at the same pO2?
Myoglobin -> fetal Hb -> normal Hb
Myoglobin has a very high affinity for oxygen and acts as an oxygen storage molecule. It only releases oxygen when the partial pressure of oxygen has fallen considerably. The function of myoglobin is to provide additional oxygen to muscles during periods of anaerobic respiration.
Name 3 molecules that shift the oxygen dissociation curve to the right when at higher levels
H+, carbon dioxide and 2,3-BPG
