Normal Erythrocytes Flashcards
Life span of mature RBCs
~120 days
Which organ removes fragile old RBCs from circulation
Spleen
Globular haemoglobin is broken down to what?
Amino acids (these then enter bloodstream)
The haem group is converted to what?
Haem group (minus iron) is converted to bilirubin
-bilirubin is transported to liver and secreted into bile
What happens to the iron?
Binds to transferrin and is recycled
What is a proerythroblast derived from?
Myeloid stem cell
What is special about the shape of red blood cells?
- diffusion distance minimised
- surface to volume ration maximised
- flexible membrane allows cells to squeeze in single file through capillaries
RBC ion balance and cell volume are actively regulated by which ENERGY-DEPENDENT PUMP?
Na+/K+ ATPase (the sodium pump)
RBC’s have no mitochondria so how do they make ATP?
Anaerobic glycolysis
-glucose is key fuel
_____ from glycolysis helps keep iron in Fe2+ state?
NADH from glycolysis helps keep iron in Fe2+ state (HbFe3+ cannot bind oxygen!!)
What is required for maintaining adequate levels of reduced glutathione? and how is it produced?
NADPH
-some glucose is metabolised through the hexose monophosphate shunt and this produces NADPH
What releases O2 from Hb?
2,3, BPG (2,3 bisphosphoglycerate)
Describe the structure of glutathione
Tripeptide consisting of glutamate, cysteine and glycine
What does reduced glutathione do?
Combats oxidative stress
-helps protect against he toxic effects of free radicals
What are free radicals?
Highly reactive molecules with unpaired electrons
-can lead to damage of cellular structures and enzymes
What is the primary intermediate in oxidative damage and what protects against its effects?
Primary intermediate is hydrogen peroxide (glutathione detoxifies it)
What is needed from the pentose phosphate pathway to produce reduced glutathione?
NADPH
How is carbon dioxide transported? and how is this facilitated?
- dissolved in solution (10%)
- bound to Hb: carbamino-haemoglobin (30%)
- as bicarbonate ion (60%)
Facilitated by CARBONIC ANHYDRASE
When fully saturated, 1g Hb will bind how many mls of oxygen?
1.34mls
Normal haemoglobin concentrations in adults?
Males: 130-180 g/l
Females: 115-165 g/l
Structure of adult haemoglobin
- 4 globin sub-units, each containing a single haem
- each haem contains a single Fe2+ ion and can bind one O2 molecule
What is co-operativity?
The influence that the binding of a ligand to one site on the molecule has on the binding of ligand to a different functional site
What facilitates the transfer of O2 from the mother to foetus?
- Foetal Hb has a higher affinity for O2 than adult
- HbF has a lower affinity for 2,3 BPG than does HbA
