Red blood cells, hemoglobin, anemias
Erythrocytes are an evolutionary solution to oxygen toxicity.
Life span of RBC ~120 days Each day we make 200 billion (iron atoms?) Each RBC contains > 1 billion atoms of iron, about 20 mg. Almost all iron comes from recycled RBCs
RBCs travel 1 passage per minute (2.8 meters), 4.7 cm per second 17 km/hr. Because of this they need to be durable. ~8 microns in width. Typical capillaries are 2-3 microns. Splenic sinusoids are 0.5 to 1 micron. RBCs need to squeeze through these and survive. Very high deformability Karl Landsteiner discovered ABO and Rh; father of transfusion science
Over 300 unique antigens on RBCs
Primary functions 1. Deliver Oxygen 2. Remove Carbon Dioxide 3. Regulates vascular flow by binding Nitric oxide
Hemoglobin 2 components 1. globin (protein) chains, 4 of these 2. heme (iron containing) group, within each globin chain
Partial Pressure of Oxygen, timed released of O2 to the tissues
Sigmoidal shape, not linear Cooperatively of binding, first oxygen bound does not bind as easily, once the first binds the second binds a bit easier, the third and fourth bind the easiest
Oxygen saturation curve and Oxygen dissociation curve
Red blood cell lacks a nucleus, RNA and DNA. Hemoglobin is a mutagen, if nucleic acid were present with it cancers would occur. So because of this when an RBC is born it has to be equipped with enough proteins to last its life cycle and not have to need to repair itself.
Cellular deformability 1) membrane flexibility, protein-cytoskeleton-lipid composition 2) cytoplasm viscosity Changes in membrane proteins, membrane structure, internal viscosity (affected by concentration of hemoglobin) dramatically affect the deformability of the red cell and affect splenetic clearance and can cause RBCs to be stuck in other organs like the brain
RBC membrane Lipid bilayer, glycophorin, actin, spectrin, ankyrin typography of living RBC is very fluid, constant fluctuation of the surface, valleys and peaks changing within fractions of seconds