Red Cell Structure and Function Flashcards
Can RBCs divide?
Nah - no nucleus
Energy for RBC?
Glycolysis
-No mitochondria
Red cells are full of?
Haemoglobin t carry oxygen (however therefore high oncotic pressure and high oxidation risk)
What is adult haemoglobin?
HbA
What does HbA consist of?
2 alpha and 2 beta globin chains
-Each globin chain has a haem group attached
What does a haem group consist of?
Fe 2+ in a flat porphyrin ring
One _______ molecule binds to 1______?
Oxygen
Ferrous iron
What is fetal Hb?
Made up of 2 gamma chains and 2 alpha chains
Immediate precursor to mature RBC erythrocyte?
Reticulocytes
Function of reticulocytes?
Contain residual ribosomal RNA and are still able to synthesis Hb
Remain in bone marrow for about 1-2 days before being released into the ciruclation where they lose their RNA and become erythrocytes
What regulated red cell production?
Erythropoietin (EPO)
What produces erythropoeitin?
Kidneys
What produces erythropoeitin?
Kidneys
What stimulates production of EPO?
Hypoxia sensed by the kidneys
EPO does what?
Stimulates bone marrow to produce more red cells
Where does red cell destruction occur normally?
Spleen and liver
Average red cell life span?
120 days
Aged red cells way of dying?
Sensed and taken out by macrophages
Globin chains in aged red cell?
Recycled to amino acids
Haem group in aged red cell?
Broken down to iron and bilirubin
What happens to bilirubin from broken down haem group?
Taken to liver and conjugated and then excreted into the bile (colours the faeces and the urine)
Erythropoiesis diagram?
What is the erythron?
RBCs are produced
Not a single organ a such just anywhere in marrow produced RBCs
What is Embden-Meryof Pathway?
Kinda just fancy name for glycolysis
Glycolysis produces?
2 ATP
2 NADH
2 Pyruvate
Production of NADH in anaerobic pathway reverse Fe3+ to?
Fe2+
Hexose monophosphate Shunt/pentose pathway?
Parallel pathway to glycolysis that produces NADPH which regenerates glutathione
What do NAPDH and Glutathione do?
Protect RBC against oxidative stress
What limits activity of Hexose monophosphate shunt/pentose pathway?
G6PD enzyme
Faulty GP6D enzyme?
Due to X-linked disorder resulting in more oxidative stress on cells and premature red cell destruction
CO2 transport?
10% dissolved in solution
30% bound directly to Hb
60% gets to lungs as bicarbonate
Dissociation curve of oxygen?
Sigmoidal
Binding of oxygen to one RBC unit?
Increases affinity of remaining subunits for oxygen, equally removal of oxygen decreases affinity
Curve for foetal Hb Oxygen dissociation?
Shifted t left meaning higher affinity for oxygen allowing it to take oxygen from maternal circulation
Myoglobin?
Monomeric in muscles
-Doesn’t show co-operativity and curve is hyperbolic
What happens in rapapoport Lubering Shunt?
Generates 2,3-BPG which
- Shifts oxygen dissociation curve to right allowing more oxygen to be released
- UPREGULATED IN ANAEMIA
Shifting the oxygen dissociation curve?
To the right: by increased H+, CO2 and temp, decreased pH
All of these would increase with respiration so makes sense that oxygen would be offloaded more readily
