Erythrocyte Membrane Structure Flashcards
(89 cards)
1
Q
Shape of RBC
A
Biconcave disc shape
2
Q
Average volume of RBC
A
90 fL (range: 80-100 fL)
3
Q
-is an RBC index that correlate to the
size or volume of the RBC
A
Mean Cell Volume
4
Q
decreased MCV
A
Microcytic
5
Q
increased MCV
A
Macrocytic
6
Q
RBC average surface area
A
140 mcm2
7
Q
Surface area of the Sphere
A
100 mcm2
8
Q
this will facilitate deformability/flexibility of the cell
A
Excess are: 40 mcm2
9
Q
RBC plasma membrane thickness
A
5 mcm
10
Q
allows RBCs to adjust to small vessels in the
microvasculature and still maintain a
constant surface area: volume ratio
A
Deformability
11
Q
-RBC indices that correlates to
the hemoglobin concentration in
relation to its size
A
Mean Cell Hemoglobin Concentration
12
Q
make the cell more viscous, it will be less
deformable, hence rigid, making the cell prone to damaged
A
high MCHC
13
Q
RBC deformability depends on:
A
- RBC geometry
- Relative cytoplasmic (hemoglobin) viscosity
- Membrane elasticity (pliancy)
14
Q
● Normal erythrocyte Hgb concentration has a _____ viscosity (fluid)
A
low
15
Q
(due to ↓ surface area)
A
Fragmentation
16
Q
(due to ↑ cell volume)
A
lysis
17
Q
Precipitated hemoglobin
A
Heinz bodies
18
Q
Polymerized hemoglobin
A
Hb S
19
Q
Crystallized hemoglobin
A
Hb C
20
Q
- it is attributed to the RBC membrane composition
A
Membrane elasticity (pliancy)
21
Q
3 Basic Functions of the RBC Membrane
A
- Regulates osmotic pressure
- Regulates cation concentration
- Regulates gas concentrations
22
Q
Lipid makes up ____ % of the RBC
A
40%
23
Q
Predominant composition in LIPID
A
phospholipids and cholesterol | cholesterol = phospholipids
24
Q
Arranged in a double layer called lipid bilayer leaflet and provides membrane fluidity
A
Phospholipids
25
-composed of 2 layers, (1) external layer towards the plasma membrane (2) the
internal layer that is directed to the
cytoplasm
Phospholipid
26
are arrayed on the membrane’s
surfaces, oriented toward both the
aqueous plasma and the
cytoplasm, respectively
hydrophilic polar head groups
27
arrange themselves to form a
central layer sequestered (hidden)
from the aqueous plasma and
cytoplasm
hydrophobic nonpolar acyl tails
28
What is the composition of the
phospholipid outer layer?
● Phosphatidylcholine
● Sphingomyelin
● Phosphatidylinositol
29
What is the predominant composition
of the phospholipid outer layer?
● phosphatidylcholine
● sphingomyelin
30
What is the composition of the
phospholipid inner layer?
● Phosphatidylethanolamine
● Phosphatidylserine
● Phosphatidylinositol
31
What is the predominant composition
of the phospholipid inner layer?
● phosphatidylethanolamine
● phosphatidylserine
32
Composition of phospholipid that is present in both layer
Phosphatidylinositol
33
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
34
Among the different phospholipids, the
________________ is the only negatively
charged.
Phosphatidylserine
35
- composed of 2 layers, (1) the inner and the
(2) outer.
Cell Membrane
36
- contains phosphatidylserine and once
the phosphatidylserine recognized by
macrophages, it will signal the
macrophages to engulf pyrenocytes.
Pyrenocytes
37
- Why is there an accumulation of
phosphatidylserine to the membrane of pyrenocytes?
Because when the cell membrane engulfed the nucleus, the cell membrane stopped and it caused the phosphatidylserine from the
inner to redistribute itself on the outermost membrane of the cell
38
The 3 Membrane-associated enzymes that maintains the structure of phospholipid:
● Scramblases
● Flippases
● Stoppases
39
Predominant: phosphatidylcholine and
sphingomyelin (with 5% glycolipid)
External Surface (Phospholipid)
40
sugar-bearing lipids | support carbohydrate side chains | anchors glycocalyx | bears blood group antigens
Glycolipids
41
- Its structures have blood group
antigens: ADH Antigen, lewis antigen,
id antigen, and different
glycophorins-associated **,
miscellaneous blood group system.
Glycolipids
42
● Predominant: phosphatidylethanolamine and phosphatidylserine
Internal surface (Phospholipid)
43
regulates membrane fluidity and membrane permeability | maintains surface area: volume ratio
Cholesterol
44
Equal proportion of phospholipids and
cholesterol = balanced tensile strength
and membrane elasticity
Unbalanced = ?
destruction of cell.
45
Cholesterol content depends on
plasma cholesterol, bile acids,
activity of LCAT (Lecithin-cholesterol
acyltransferase)
46
Alteration in the cholesterol content in
cell = ?
abnormal cell/susceptible to damage
47
Abnormal L/S ratio
Acanthocyte
48
: ↑ cholesterol, phospholipids
Codocyte
49
: ↓ cholesterol
Ovalocyte
50
percent of Carbohydrate in RBC
8%
51
● layer of carbohydrates whose net
negative charge prevents
microbial attack and protects the
RBC from mechanical damage
● surface carbohydrates joined with
glycolipids
Glycocalyx
52
percent of Protein in RBC
52%
53
contains sialic acid which gives RBCs a negative charge
Integral Proteins / Transmembrane Proteins
54
- makes RBC do not collide once they
are in circulation. No occurrence of auto-agglutination/auto-aggregation in
the blood vessels.
Sialic acid
55
Functions of Protein in RBC
- Transport Site
- Adhesion Site
- Signaling Receptors
56
principal integral CHON
Band 3 protein
57
2 macromolecular complexes of
integral proteins:
1. Ankyrin complex
2. Protein 4.1 complex / Actin junctional complex
58
Major components → band 3 multimers
and protein 4.2
Ankyrin complex
59
Major components → band 3 dimers,
protein 4.2 and adducin
Protein 4.1 complex/Actin junctional complex
60
band 3 + protein 4.2 will anchor the
phospholipid layer to the spectrin
cytoskeleton to ankyrin
Ankyrin Complex
61
- band 3 dimers + protein 4.2 and
adducin = anchor the phospholipid layer
to spectrin cytoskeleton to the protein
Protein 4.1 complex/Actin Junctional complex
62
Major Functions of INTEGRAL PROTEINS:
- Anchored to peripheral proteins/work
together inoder to prevent the loss of
lipid bilayer.
- provide membrane structural integrin
63
TMP
water transporter and creates spore/channel to the membrane of RBC to regulate
water content of they cell
Aquaporin 1
64
↓ Aquaporin 1 = ?
uncontrollable water content →
bursting/swelling of cells (Hereditary Spherocytosis)
65
TMP
anion transfer, supports ABD antigen.
- Regulates movements of:
● chloride
● bicarbonate
- Important anions in the RBC.
Band 3 / Anion Exchanger 1
66
TMP
regulates the calcium inside the cell
Calcium Pump/ Ca2+ ATPase - Ca2+ transporter
67
TMP
Glucose transporter and supports ABH antigens.
- responsible in the entry of plasma glucose
needed for anaerobic glycolysis.
Glut 1
68
TMP
- regulates sodium and
potassium in and out of
the cell.
Sodium ATPase/Sodium
Potassium Pump - Sodium
Potassium transporter
69
● Integral CHONs + peripheral CHONs:
○ Prevents loss of lipid bilayer
○ Provides membrane structural integrity
70
principal cytoskeletal CHONs
α-spectrin and β-spectrin (bands 1 and 2, respectively)
71
key regulators of membrane elasticity and mechanical stability à unfolding and refolding of cytoskeleton of the cell; which is the
primary reason why RBC membrane is
flexible, and elastic.
α spectrin and β-spectrin along with protein 4.1 junction
72
● Other cytoskeletal CHONs:
F-actin (band 5), adducin, ankyrin, dematin, tropomodulin, tropomyosin
73
Protein Junctional Complex / Protein 4.1 Complex comprises of:
● Band 3
● Protein 4.2
● Adducin
74
stabilizes the actin junctional
complex (Protein 4.1 Complex), and is
also responsible for the maintenance of
RBC shape
dematin
75
RBC membrane is composed of:
● Lipids – phosphatidylcholine, sphingomyelin, inositol, ethanolamine, serine
● Carbohydrates – glycocalyx
● Proteins – integral and peripheral proteins
● Cholesterol
76
RBC membrane is impermeable to:
* Na+
* K+
* Ca2+
77
RBC membrane is permeable to:
* H2O
* HCO3-
* Cl
78
What are the essential proteins in the
Osmotic Balance and Impermeability?
1. Aquaporin 1
2. ATP-Dependent Cation Pumps
79
Intracellular (Na: K ratio) →
1:12
80
Extracellular (Na: K ratio) →
25:1
81
controls active transport of sodium & potassium
Na+, K+, ATPase:
82
Uncontrolled sodium influx; water always follows the direction of sodium à water will enter the cell, making the cell swell à
CELL LYSIS
83
Uncontrolled concentration of potassium. In cases of high potassium concentration, the sodium concentration heavily decreases à
CELL SHRINKAGE
84
maintains low intracellular Ca2+ levels (5-10
μmol/L)
Ca2+ - ATPase
85
controls the function of Ca2+ - ATPase
Calmodulin
86
is an enzyme that maintains the low intracellular calcium levels.
Calcium Pump
87
Would result to uncontrolled influx of calcium à cell will become rigid, less deformable, susceptible to damage
Defective Calcium Pump
88
Colloid Osmotic Hemolysis:
● ATP loss or Pump damage → Na+, Ca2+ influx → water enters the cell → swelling
(spheroid) → rupture
89
● condition where RBCs rupture because of the ATP loss or pump damage, there will be no control for the influx of sodium and calcium
Colloid Osmotic Hemolysis
