Normal Red Blood Cells Flashcards
What is the result of red blood cells being full of haemoglobin?
They have a high oncotic pressure and an oxygen rich environment
What is the result of red blood cells having no nucleus?
They can’t divide or replace damaged proteins so they have a limited lifespan
What is the result of red blood cells having no mitochondria?
Limited to glycolysis for energy generation
Describe the membrane of a red blood cell?
Contains protein spars and protein anchors to make it flexible
What happens if there is damage to the proteins within a red cell membrane?
They will become inflexible and won’t be able to pass through capillaries
Describe briefly what happens in the sodium potassium pump? What is the function of this in red blood cells?
K+ in, Na+ out / keeps water out
Describe the basic structure of a haemoglobin molecule?
A tetrameric globular protein
Each globular protein of haemoglobin contains what? And this contains what? Which does what?
A haem group / Iron / holds onto the oxygen molecule
What chains is a) adult and b) foetal haemoglobin composed of?
a) 2 alpha and 2 beta b) 2 alpha and 2 gamma
Within haemoglobin, one oxygen molecule binds to what?
One Fe2+ molecule
Why does oxygen not bind to Fe3+?
Because this is already oxidised
What are the main functions of haemoglobin?
Deliver oxygen to tissues, act as a buffer for H+, involved in CO2 transport
Describe briefly the regulation of RBC production i.e the role of erythropoietin?
Hypoxia is sensed by the kidneys which stimulates erythropoietin to be produced. This stimulates more red blood cell development and then erythropoietin levels drop back to normal
Destruction of red blood cells usually occurs where? The red blood cells are taken out of the circulation by what?
Spleen / macrophages
How are the contents of red blood cells broken down?
Globin chains are recycled to amino acids / haem group is broken down into iron which gets recycled and bilirubin which is taken to the liver and excreted in the urine and faeces as bile
How does a red blood cell get energy? What is the net gain of ATP in this process?
Glycolysis / 2 ATP
How does an RBC prevent Fe2+ from becoming Fe3+?
The process of glycolysis produced NADH which acts as a reducing agent and protects the Fe2+ from oxidation
What are some examples of free radicals which could potentially cause damage to enzymes and Hb?
Superoxide and hydrogen peroxide
What molecule protects us from free radical damage from hydrogen peroxide? How?
Glutathione - it reacts with hydrogen peroxide to form water and oxidised glutathione (GSSG)
Glutathione which has been oxidised can be replenished via which other molecule? Which process is responsible for producing this?
NADPH / hexose monophosphate shunt
What is the rate limiting enzyme in the hexose monophosphate shunt?
Glucose 6 phosphate dehydrogenase
What are the ways that CO2 can travel to the lungs?
10% dissolved in solution, 30% bound directly to Hb as carbamino-Hb and 60% as bicarbonate
How many oxygen molecules are bound to one Hb?
4
What is the relationship between oxygen being bound to haemoglobin in a) the lungs (high pO2) and b) the tissues (low pO2)?
a) oxygen is bound to Hb (fully saturated) b) haemoglobin gives up oxygen to the tissues (desaturated)
What is the shape of the oxygen-haemoglobin dissociation curve? Why is this?
Sigmoidal / due to allosteric binding
Describe what is meant by allosteric/co-operative binding of oxygen and haemoglobin?
Once one oxygen molecule has bound to an Hb subunit, it becomes easier for further units to bind
On the oxygen dissociation curve, what way will foetal Hb be shifted compared with adult Hb? Why?
Left - it saturates more at the same pO2
What does it mean if the oxygen haemoglobin dissociation curve is shifted to the a) right? b) left?
a) less oxygen is bound to haemoglobin, more oxygen is being delivered to the tissue b) more oxygen is bound to haemoglobin, less oxygen is being delivered to the tissues
What are some factors which may shift the oxygen dissociation curve to the right?
Decreased pH, increased 2,3-BPG and increased temperature
What are some factors which may shift the oxygen dissociation curve to the left?
Increased pH, decreased 2,3-BPG, decreased temperature
