RBC membrane Structure Flashcards
Average volume of RBC
90 fL (range: 80-100 fL)
Average surface area of RBC
140 μm2
________________of RBCs facilitates its oxygen-carbon dioxide transport function.
Biconcave disc shape of RBCs
allows RBCs to adjust to small vessels in the microvasculature and still maintain a constant surface area: volume ratio
Deformability
RBC deformability depends on:
- RBC geometry
- Relative cytoplasmic (hemoglobin) viscosity
- Membrane elasticity (pliancy)
Normal erythrocyte Hgb concentration has a _______ viscosity (fluid)
low
↓ water and hemoglobin (precipitated, polymerized, or crystallized) →
Less deformable which leads to cell lysis
Precipitated hemoglobin leads to the formation of
Heinz bodies
Polymerized hemoglobin leads to the formation of
Hemoglobin S
Crystallized hemoglobin leads to the formation of
Hemoglobin C
Changes in the surface area to volume ratio causes?
RBC fragmentation and lysis
Fragmentation is due to?
The decrease in surface area
Lysis is due to?
The increase in cell volume
3 basic functions of the RBC membrane
- Regulates osmotic pressure
- Regulates cation concentration
- Regulates gas concentrations
Percentage of lipids
40%
Predominant in lipids
phospholipids and cholesterol
Arranged in a double layer called lipid bilayer leaflet |provides membrane fluidity
Phospholipids
Predominant in external surface of Phospholipids
phosphatidylcholine and sphingomyelin (with 5% glycolipid)
sugar-bearing lipids
support carbohydrate side chains
anchors glycocalyx
bears blood group antigens
Glycolipid
Predominant in the internal surface of phospholipids
phosphatidylethanolamine and phosphatidylserine
regulates membrane fluidity and membrane permeability
maintains surface area:volume ratio
Cholesterol