red blood cell structure and function Flashcards
how many polypeptide chains does heamoglobin contain
4
what are the 4 polypeptide chains
2 alpha globin chains
2 beta globin chains
where does ferrous iron come from
circulating transferring and protoporphyrin
what is the synthesis of red blood cells called
erythropeoisis
what does carbon dioxide combine with and what does this create
water to produce carbonic acid
what enzyme produces carbonic acid
carbonic anhydrase
what is the chloride shift
carbonic acid breaks down into H+ and HCO3-
HCO3- moves out in exchange with Cl-
what is most CO2 transported as
bicarbonate
how is haemoglobin produced
Glycine and succinyl coA react to produce protoporphyrin - this is synthesised by ALA-synthase pyroxidine
protoporphyrin then combines with Fe+ to form the haem group
this then combines with globin to produce heamoglobin
what is the first recognisable RBC precursor in the bone marrow
proerothroblast
what does the proerothroblast undergo maturation into in the marrow
late normoblast
what happens to form a reticulocyte
the nucleus is extruded when pushed into the blood - this contains some residual ribosomal RNA and so can still synthesise some haemoglobin (however after a couple of days in the blood the RNA degrades and the mature RBC cannot synthesise any more heamoglobin)
what stimulates erythropoiesis
erythropoietin
what is erythropoietin
a glycosylated peptide mostly produced in the kidney
when is there major production of erythropoietin
when theres low oxygen tensions
how does lower oxygen tensions cause the release of erythropoeiten
because RBCs give oxygen to the kidneys which have oxygen sensors
if oxygen levels are low then this causes the peritubular interstitial cells of the outer cortex to release more erythropoietin
when does erythropoietin act on
the later stages of RBC maturation when it still has a nucleus
what is special about the RBC membrane
lipid bilayer
what does the inside of the lipid bilayer contain
spectrin ankyrin actin protein 4.1 band 3 proteins (anion channels) carbohydrate chains
how do RBC derive their energy
from glycolytic pathways
what controls the oxygen-deoxygynation of haemoglobin
2,3, DPG
when haemoglobin is oxygenated there is no space for 2,3 DPG to fit in
when deoxygenated 2,3 DPG can fit in the middle and allow rapid release of O2
where is prenatal heamoglobin synthesised
in the yolk sac, then the liver and then the spleen.
RBC’s under normal circumstances are broken down how
extravascularly in macrophages
what is protoporphyrine converted into
bilirubin
how does RBC lysis occur abnormally
intra-vascular
where are the hydrophilic AA’s postitioned
project outwards making RBC soluble
where are the hydrophobic AA’s positioned
project inwards making interior of Hb water repellant
what is protoporphyrine anchored by
F8 histadine
what are the chemical bonds that hold the quaternary structure of haemoglobin together
ionic, hydrogen and van der waals
