RBC Metabolism/Membrane

metabolic requirements

active cation transport
preserving deformability

maintain erythrocyte function

Hgb function
Reduced Pyridine Nucleotides
2,3-DPG

hemoglobin function

oxidants → globin denaturation → heinz bodies
phosphogluconate pathway provides the glutathione and NADPH to guel
Neutralizes oxidants (Prevention)

Erythrocyte Membrane Function

to contain Hgb and other cytoplasmic components
to provide a surface for receptors

external surface

dark
hydrophilic
glycolipid
glycoprotein
protein

middle layer

light
hydrophobic
phospholipid
cholesterol
protein (hydrophobic stretches)

cytoplasmic surface

dark
hydrophilic
protein

Phosphlipids

glycerol + 3 fatty acids = triglyceride
ATP donates a phosphate
one fatty acid is removed
polar head + 2 fatty acid tails

choline phosphlipid

outer half of lipid bilayer
lipid renewal

amino phosphlipid

inside half of the membrane

Glycolipids

outer half of the membrane
RBC antigens

RBC antigens

glycolipids + glycoproteins

Cholesterol

25% of total membrane lipid
1:1 molar ratio with phospholipids
continual exchange with plasma

increased cholesterol

causes target cells, acanthocytes, and decreased survival

glycophorin

integral membrane protein
10% membrane, 60% carbohydrate/sialic,
spans entire membrane
antigens, receptors and transport proteins

spectrin

peripheral membrane protein
25% membrane,
alpha beta heterodimer,
cytoskeleton,
deform/perm

carbohydrates

external surface, ABO antigens, receptors

actin

contractile protein

permeable molecules

sugars
H2O
anions (chloride and bicarbonate)

impermeable molecules

proteins
ATP
Cations (sodium and potassium)