Erythrocyte Membrane Structure Flashcards
Shape of RBC
Biconcave disc shape
Average volume of RBC
90 fL (range: 80-100 fL)
-is an RBC index that correlate to the
size or volume of the RBC
Mean Cell Volume
decreased MCV
Microcytic
increased MCV
Macrocytic
RBC average surface area
140 mcm2
Surface area of the Sphere
100 mcm2
this will facilitate deformability/flexibility of the cell
Excess are: 40 mcm2
RBC plasma membrane thickness
5 mcm
allows RBCs to adjust to small vessels in the
microvasculature and still maintain a
constant surface area: volume ratio
Deformability
-RBC indices that correlates to
the hemoglobin concentration in
relation to its size
Mean Cell Hemoglobin Concentration
make the cell more viscous, it will be less
deformable, hence rigid, making the cell prone to damaged
high MCHC
RBC deformability depends on:
- RBC geometry
- Relative cytoplasmic (hemoglobin) viscosity
- Membrane elasticity (pliancy)
● Normal erythrocyte Hgb concentration has a _____ viscosity (fluid)
low
(due to ↓ surface area)
Fragmentation
(due to ↑ cell volume)
lysis
Precipitated hemoglobin
Heinz bodies
Polymerized hemoglobin
Hb S
Crystallized hemoglobin
Hb C
- it is attributed to the RBC membrane composition
Membrane elasticity (pliancy)
3 Basic Functions of the RBC Membrane
- Regulates osmotic pressure
- Regulates cation concentration
- Regulates gas concentrations
Lipid makes up ____ % of the RBC
40%
Predominant composition in LIPID
phospholipids and cholesterol | cholesterol = phospholipids
Arranged in a double layer called lipid bilayer leaflet and provides membrane fluidity
Phospholipids
-composed of 2 layers, (1) external layer towards the plasma membrane (2) the
internal layer that is directed to the
cytoplasm
Phospholipid
are arrayed on the membrane’s
surfaces, oriented toward both the
aqueous plasma and the
cytoplasm, respectively
hydrophilic polar head groups
arrange themselves to form a
central layer sequestered (hidden)
from the aqueous plasma and
cytoplasm
hydrophobic nonpolar acyl tails
What is the composition of the
phospholipid outer layer?
● Phosphatidylcholine
● Sphingomyelin
● Phosphatidylinositol
What is the predominant composition
of the phospholipid outer layer?
● phosphatidylcholine
● sphingomyelin
What is the composition of the
phospholipid inner layer?
● Phosphatidylethanolamine
● Phosphatidylserine
● Phosphatidylinositol
What is the predominant composition
of the phospholipid inner layer?
● phosphatidylethanolamine
● phosphatidylserine
Composition of phospholipid that is present in both layer
Phosphatidylinositol
are the one that bear copies
of carbohydrate-based blood group
antigens, such as antigens of the ABH and
the Lewis blood group systems.
Glycolipids
Among the different phospholipids, the
________________ is the only negatively
charged.
Phosphatidylserine
- composed of 2 layers, (1) the inner and the
(2) outer.
Cell Membrane