Biochemistry Flashcards
what are properties of a mature RBC
Packed with haemoglobin (Hb)
No nucleus or mitochondria
No DNA/RNA, therefore no cell division
what is the life span of a RBC
120 days
spleen removes old RBC from circulation
what happens to old RBCs
recycled by phagocytic cells of the liver and spleen
what is the RBC broken down to
Haemoglobin broken down to»_space; amino acids
Haem group (minus iron) is converted to bilirubin
Iron binds to transferrin in the blood and is recycled
where does bilirubin go
transported to the liver and secreted into bile
Bilirubin breakdown products colour urine and faeces
what regulates erythrocyte production
erythropoietin (EPO) produced by the kidney
what causes the kidney to release EPO
hypoxia
what are the steps of erythropoiesis
1 - proerythroblast (derived from myeloid stem cells)
2 - polychromatic erythroblast (Hb appears in cytoplasm)
3 - orthochromatic erythroblast (nucleus shrinks, full complement of Hb in cytoplasm)
4 - erythroblast extrudes nucleus
5 - reticulocyte into circulation
6 - mature RBC/erythrocyte
what is the structure of a RBC and why is it important
biconcave disc
- increases SA
- flexible membrane so cell can squeeze through capillaries
- decreased diffusion distance
what is the percentage of what blood is composed of
55% plasma
1% platelets + WBC
40-50% RBC (in males)
36-46% RBC (in females)
how is a RBC ion balance and cell volume regulated
energy-dependent Na+/K+ ATPases (‘the sodium pump’)
through what route does a RBC do ATP synthesis
anaerobic glycolysis
no mitochondria so cannot do aerobic glycolysis
what from glycolysis keeps iron in the Fe2+ state
NADH
what release oxygen from haemoglobin when we move to a higher altitude
2,3 BPG (biphosphoglycerate)
what is Glutathione
Tripeptide, consisting of glutamate, cysteine, and glycine
what is the role of Glutathione
Reduced glutathione (GSH) combats oxidative stress i.e. an antioxidant
maintains normal reduced state in a cell
what are free radicals
highly reactive molecules with unpaired electrons
what would happen if we had excessive free radicals or inadequate antioxidants
damage of cellular structures and enzymes
what is the importance of glutathione
helps protect against the toxic effects of reactive oxygen species (free radicals)
essential to de-toxify hydrogen peroxide
what is needed to produce glutathione
NADPH from the pentose phosphate pathway
how is CO2 carried to the lungs
1- Physically dissolved in solution (amount ∝ Pco2)
2 - Bound to Hb – carbamino-haemoglobin
3 - As bicarbonate ion – HCO3-
how is the movement of CO2 facilitated
by carbonic anhydrase
what is haemoglobin comprised of
4 globin (protein) sub-units, each containing a single haem molecule
what does each haem molecule contain
single Fe2+ ion
porphyrin ring
