Erythrocytes Flashcards
What are features of a mature erythrocyte
Packed with haemoglobin no nucleus or mitochondria no DNA / RNA / cell division 120 day life span old fragile RBC's removed by spleen generated in red bone marrow
What happens to old erythrocytes
phagocytic cells in liver and spleen engulf old RBC
Haemoglobin proteins broken down into amino acids
Haem group converted to bilirubin
bilirubin is taken to liver and is secreted into bile
iron binds to transferrin in blood and is recycled
What hormone controls erythropoiesis and what organ secretes it
Erythropoietin
secreted by kidney
What is main site of erythropoiesis
bone marrow
What is haematocrit
percentage of blood that is RBC
How does erythrocyte generate ATP
glycolysis
NADH is product of glycolysis, what does NADH do to iron?
helps maintain iron as its Fe2+ ionic state
How is ionic homeostasis maintained in an erythrocyte
Na / K ATPase transporters
what are the products of Glyoclysis
requires 2 ATP
generates 4 ATP and 2 NADH
(can also produce NADPH)
How is NADPH formed in glycolysis
when fructose-6-phosphate is redirected to Hexose monophosphate, pentose phosphate pathway
What is oxidative stress
imbalance in production of free radicals and bodies ability to detoxify them with antioxidants
leads to cell damage
What is glutathione
Tripeptide containing glutamate, cysteine, glycine
What does reduced glutathione do
combats oxidative stress
maintains normal reduced state in cell
How does glutathione combat oxidative stress
detoxifies H2O2 (hydrogen peroxide) which is primary intermediate of oxidative damage
What does NADPH do
Keeps iron as ferrous ion (Fe2+)
reduces glutathione
insufficiency of production of NADPH from pentose pathway can lead to what
cell damage via oxidative damage from free radicals
How is CO2 transported in blood?
dissolved in solution 10%
bound to Hb 30%
Bicarbonate ion 60%
Once CO2 has dissolved into RBC, how is it converted to bicarbonate
CO2 + H20 H2CO3 H+ + HCO3-
What enzyme facilitates the conversion of CO2 to bicarbonate in RBC?
carbonic anhydrase
What happens to bicarbonate in RBC once formed?
transported out of cell and into plasma via
HCO3- / Cl- transporter
Cl- comes in to cell to maintain cell membrane potential
What are hydrogen ions (biproduct of bicarbonate formation) buffered by?
deoxygenated haemoglobin
Hb - + H+ = HHb
As bicarbonate is driven out of cell, and Cl- is transported in to cell to compensate, what happens to cell?
Cell swells (at tissue)
As bicarbonate is transported into cell and chloride is transported out of cell to compensate, what happens to cell
cell shrinks (at lungs)
What are the constituents of adult haemoglobin
4 globin (protein) subunits each containing a single haem
4 Haem groups total
Each haem group contains one Fe2+ ion
each haem group binds one O2 molecule
What is the haem group
porphyrin ring
What subunits of globin exist in haemoglobin molecule in adults
2 alpha and 2 beta
2 alpha and 2 gamma in fetus
Describe basic mechanism by witch oxygen is transported along placenta to fetus
Fetal haemoglobin has higher affinity for oxygen than adult haemoglobin
therefore oxygen will transport from adult haemoglobin to fetal haemoglobin
explain G6PD deficiency
G6PD is an enzyme in the pentose phosphate pathway which is how NADPH is manufactured. If you have a deficiency in this enzyme then you cannot produce NADPH and therefore cannot combat oxidative stress
