Erythrocyte Membrane Structure Flashcards

1
Q

Shape of RBC

A

Biconcave disc shape

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2
Q

Average volume of RBC

A

90 fL (range: 80-100 fL)

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3
Q

-is an RBC index that correlate to the
size or volume of the RBC

A

Mean Cell Volume

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4
Q

decreased MCV

A

Microcytic

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5
Q

increased MCV

A

Macrocytic

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6
Q

RBC average surface area

A

140 mcm2

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7
Q

Surface area of the Sphere

A

100 mcm2

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8
Q

this will facilitate deformability/flexibility of the cell

A

Excess are: 40 mcm2

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9
Q

RBC plasma membrane thickness

A

5 mcm

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10
Q

allows RBCs to adjust to small vessels in the
microvasculature and still maintain a
constant surface area: volume ratio

A

Deformability

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11
Q

-RBC indices that correlates to
the hemoglobin concentration in
relation to its size

A

Mean Cell Hemoglobin Concentration

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12
Q

make the cell more viscous, it will be less
deformable, hence rigid, making the cell prone to damaged

A

high MCHC

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13
Q

RBC deformability depends on:

A
  • RBC geometry
  • Relative cytoplasmic (hemoglobin) viscosity
  • Membrane elasticity (pliancy)
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14
Q

● Normal erythrocyte Hgb concentration has a _____ viscosity (fluid)

A

low

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15
Q

(due to ↓ surface area)

A

Fragmentation

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16
Q

(due to ↑ cell volume)

A

lysis

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17
Q

Precipitated hemoglobin

A

Heinz bodies

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18
Q

Polymerized hemoglobin

A

Hb S

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19
Q

Crystallized hemoglobin

A

Hb C

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20
Q
  • it is attributed to the RBC membrane composition
A

Membrane elasticity (pliancy)

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21
Q

3 Basic Functions of the RBC Membrane

A
  1. Regulates osmotic pressure
  2. Regulates cation concentration
  3. Regulates gas concentrations
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22
Q

Lipid makes up ____ % of the RBC

A

40%

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23
Q

Predominant composition in LIPID

A

phospholipids and cholesterol | cholesterol = phospholipids

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24
Q

Arranged in a double layer called lipid bilayer leaflet and provides membrane fluidity

A

Phospholipids

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25
Q

-composed of 2 layers, (1) external layer towards the plasma membrane (2) the
internal layer that is directed to the
cytoplasm

A

Phospholipid

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26
Q

are arrayed on the membrane’s
surfaces, oriented toward both the
aqueous plasma and the
cytoplasm, respectively

A

hydrophilic polar head groups

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27
Q

arrange themselves to form a
central layer sequestered (hidden)
from the aqueous plasma and
cytoplasm

A

hydrophobic nonpolar acyl tails

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28
Q

What is the composition of the
phospholipid outer layer?

A

● Phosphatidylcholine
● Sphingomyelin
● Phosphatidylinositol

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29
Q

What is the predominant composition
of the phospholipid outer layer?

A

● phosphatidylcholine
● sphingomyelin

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30
Q

What is the composition of the
phospholipid inner layer?

A

● Phosphatidylethanolamine
● Phosphatidylserine
● Phosphatidylinositol

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31
Q

What is the predominant composition
of the phospholipid inner layer?

A

● phosphatidylethanolamine
● phosphatidylserine

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32
Q

Composition of phospholipid that is present in both layer

A

Phosphatidylinositol

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33
Q

are the one that bear copies
of carbohydrate-based blood group
antigens, such as antigens of the ABH and
the Lewis blood group systems.

A

Glycolipids

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34
Q

Among the different phospholipids, the
________________ is the only negatively
charged.

A

Phosphatidylserine

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35
Q
  • composed of 2 layers, (1) the inner and the
    (2) outer.
A

Cell Membrane

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36
Q
  • contains phosphatidylserine and once
    the phosphatidylserine recognized by
    macrophages, it will signal the
    macrophages to engulf pyrenocytes.
A

Pyrenocytes

37
Q
  • Why is there an accumulation of
    phosphatidylserine to the membrane of pyrenocytes?
A

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
Q

The 3 Membrane-associated enzymes that maintains the structure of phospholipid:

A

● Scramblases
● Flippases
● Stoppases

39
Q

Predominant: phosphatidylcholine and
sphingomyelin (with 5% glycolipid)

A

External Surface (Phospholipid)

40
Q

sugar-bearing lipids | support carbohydrate side chains | anchors glycocalyx | bears blood group antigens

A

Glycolipids

41
Q
  • Its structures have blood group
    antigens: ADH Antigen, lewis antigen,
    id antigen, and different
    glycophorins-associated **,
    miscellaneous blood group system.
A

Glycolipids

42
Q

● Predominant: phosphatidylethanolamine and phosphatidylserine

A

Internal surface (Phospholipid)

43
Q

regulates membrane fluidity and membrane permeability | maintains surface area: volume ratio

A

Cholesterol

44
Q

Equal proportion of phospholipids and
cholesterol = balanced tensile strength
and membrane elasticity

Unbalanced = ?

A

destruction of cell.

45
Q

Cholesterol content depends on

A

plasma cholesterol, bile acids,
activity of LCAT (Lecithin-cholesterol
acyltransferase)

46
Q

Alteration in the cholesterol content in
cell = ?

A

abnormal cell/susceptible to damage

47
Q

Abnormal L/S ratio

A

Acanthocyte

48
Q

: ↑ cholesterol, phospholipids

A

Codocyte

49
Q

: ↓ cholesterol

A

Ovalocyte

50
Q

percent of Carbohydrate in RBC

A

8%

51
Q

● layer of carbohydrates whose net
negative charge prevents
microbial attack and protects the
RBC from mechanical damage
● surface carbohydrates joined with
glycolipids

A

Glycocalyx

52
Q

percent of Protein in RBC

A

52%

53
Q

contains sialic acid which gives RBCs a negative charge

A

Integral Proteins / Transmembrane Proteins

54
Q
  • makes RBC do not collide once they
    are in circulation. No occurrence of auto-agglutination/auto-aggregation in
    the blood vessels.
A

Sialic acid

55
Q

Functions of Protein in RBC

A
  • Transport Site
  • Adhesion Site
  • Signaling Receptors
56
Q

principal integral CHON

A

Band 3 protein

57
Q

2 macromolecular complexes of
integral proteins:

A
  1. Ankyrin complex
  2. Protein 4.1 complex / Actin junctional complex
58
Q

Major components → band 3 multimers
and protein 4.2

A

Ankyrin complex

59
Q

Major components → band 3 dimers,
protein 4.2 and adducin

A

Protein 4.1 complex/Actin junctional complex

60
Q

band 3 + protein 4.2 will anchor the
phospholipid layer to the spectrin
cytoskeleton to ankyrin

A

Ankyrin Complex

61
Q
  • band 3 dimers + protein 4.2 and
    adducin = anchor the phospholipid layer
    to spectrin cytoskeleton to the protein
A

Protein 4.1 complex/Actin Junctional complex

62
Q

Major Functions of INTEGRAL PROTEINS:

A
  • Anchored to peripheral proteins/work
    together inoder to prevent the loss of
    lipid bilayer.
  • provide membrane structural integrin
63
Q

TMP
water transporter and creates spore/channel to the membrane of RBC to regulate
water content of they cell

A

Aquaporin 1

64
Q

↓ Aquaporin 1 = ?

A

uncontrollable water content →
bursting/swelling of cells (Hereditary Spherocytosis)

65
Q

TMP
anion transfer, supports ABD antigen.
- Regulates movements of:
● chloride
● bicarbonate
- Important anions in the RBC.

A

Band 3 / Anion Exchanger 1

66
Q

TMP
regulates the calcium inside the cell

A

Calcium Pump/ Ca2+ ATPase - Ca2+ transporter

67
Q

TMP
Glucose transporter and supports ABH antigens.
- responsible in the entry of plasma glucose
needed for anaerobic glycolysis.

A

Glut 1

68
Q

TMP
- regulates sodium and
potassium in and out of
the cell.

A

Sodium ATPase/Sodium
Potassium Pump - Sodium
Potassium transporter

69
Q

● Integral CHONs + peripheral CHONs:

A

○ Prevents loss of lipid bilayer
○ Provides membrane structural integrity

70
Q

principal cytoskeletal CHONs

A

α-spectrin and β-spectrin (bands 1 and 2, respectively)

71
Q

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.

A

α spectrin and β-spectrin along with protein 4.1 junction

72
Q

● Other cytoskeletal CHONs:

A

F-actin (band 5), adducin, ankyrin, dematin, tropomodulin, tropomyosin

73
Q

Protein Junctional Complex / Protein 4.1 Complex comprises of:

A

● Band 3
● Protein 4.2
● Adducin

74
Q

stabilizes the actin junctional
complex (Protein 4.1 Complex), and is
also responsible for the maintenance of
RBC shape

A

dematin

75
Q

RBC membrane is composed of:

A

● Lipids – phosphatidylcholine, sphingomyelin, inositol, ethanolamine, serine
● Carbohydrates – glycocalyx
● Proteins – integral and peripheral proteins
● Cholesterol

76
Q

RBC membrane is impermeable to:

A
  • Na+
  • K+
  • Ca2+
77
Q

RBC membrane is permeable to:

A
  • H2O
  • HCO3-
  • Cl
78
Q

What are the essential proteins in the
Osmotic Balance and Impermeability?

A
  1. Aquaporin 1
  2. ATP-Dependent Cation Pumps
79
Q

Intracellular (Na: K ratio) →

A

1:12

80
Q

Extracellular (Na: K ratio) →

A

25:1

81
Q

controls active transport of sodium & potassium

A

Na+, K+, ATPase:

82
Q

Uncontrolled sodium influx; water always follows the direction of sodium à water will enter the cell, making the cell swell à

A

CELL LYSIS

83
Q

Uncontrolled concentration of potassium. In cases of high potassium concentration, the sodium concentration heavily decreases à

A

CELL SHRINKAGE

84
Q

maintains low intracellular Ca2+ levels (5-10
μmol/L)

A

Ca2+ - ATPase

85
Q

controls the function of Ca2+ - ATPase

A

Calmodulin

86
Q

is an enzyme that maintains the low intracellular calcium levels.

A

Calcium Pump

87
Q

Would result to uncontrolled influx of calcium à cell will become rigid, less deformable, susceptible to damage

A

Defective Calcium Pump

88
Q

Colloid Osmotic Hemolysis:

A

● ATP loss or Pump damage → Na+, Ca2+ influx → water enters the cell → swelling
(spheroid) → rupture

89
Q

● condition where RBCs rupture because of the ATP loss or pump damage, there will be no control for the influx of sodium and calcium

A

Colloid Osmotic Hemolysis