The main characteristics of the erythrocyte cell membrane and relate these to the function of erythrocyte.

Organization of erythrocyte membrane

 

Human erythrocytes are small cells that lack nuclei when mature they appear as circular biconcave discs.

• The membrane structure agrees with the Fluid Mosaic Model.
• “the membrane protein ,intrinsic proteins(integral) deeply embedded and peripheral proteins loosely attached, that in an environment of fluid phospholipid bilayer.”
• Fluidity of the membrane largely depends on the lipid composition of the membrane
•  Due to presence of phospholipids erythrocyte membrane has high fluidity & flexibility.
  
  

• Biconcave shape, 7-8 µm diameter, 2.2 µm thick.
• Results in larger surface area to volume ratio than a sphere. Increase efficiency of gas exchange. 
• Cells very thin- efficient diffusion of gases across the surface.
 
• The shape and fluidity of membrane makes it flexible.
• Allows it to squeeze through capillaries whose internal diameters are than its own by bending into shapes like umbrella tops.
 
•  Presence of integral proteins.
 
• Glycophorin
• Glycoprotein
• Some of the oligosaccharides of the glycophorin are the M and N blood group antigens.
• Other CHOs , bound to glycophorin are sites through which the influenza virus becomes attached to RBCs.
 
• Band-3-protein- membrane transport protein As RBCs flow through capillaries of lungs, these exchanges HCO₃^- for Cl^- ions.
 
• Presence of peripheral proteins.
• The inner face of RBC membrane is laced with a network of proteins called cytoskeleton
• It stabilizes the membrane
• Responsible for the biconcave shape.
• The proteins participating are,

                        Spectrin

                        Actin

                        Ankyrin & Band 4 protein