RBC membrane Structure

Question 1

Average volume of RBC

Answer 1

90 fL (range: 80-100 fL)

Question 2

Average surface area of RBC

Answer 2

140 μm2

Question 3

________________of RBCs facilitates its oxygen-carbon dioxide transport function.

Answer 3

Biconcave disc shape of RBCs

Question 4

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

Answer 4

Deformability

Question 5

RBC deformability depends on:

Answer 5

1. RBC geometry
2. Relative cytoplasmic (hemoglobin) viscosity
3. Membrane elasticity (pliancy)

Question 6

Normal erythrocyte Hgb concentration has a _______ viscosity (fluid)

Answer 6

low

Question 7

↓ water and hemoglobin (precipitated, polymerized, or crystallized) →

Answer 7

Less deformable which leads to cell lysis

Question 8

Precipitated hemoglobin leads to the formation of

Answer 8

Heinz bodies

Question 9

Polymerized hemoglobin leads to the formation of

Answer 9

Hemoglobin S

Question 10

Crystallized hemoglobin leads to the formation of

Answer 10

Hemoglobin C

Question 11

Changes in the surface area to volume ratio causes?

Answer 11

RBC fragmentation and lysis

Question 12

Fragmentation is due to?

Answer 12

The decrease in surface area

Question 13

Lysis is due to?

Answer 13

The increase in cell volume

Question 14

3 basic functions of the RBC membrane

Answer 14

1. Regulates osmotic pressure
2. Regulates cation concentration
3. Regulates gas concentrations

Question 15

Percentage of lipids

Answer 15

40%

Question 16

Predominant in lipids

Answer 16

phospholipids and cholesterol

Question 17

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

Answer 17

Phospholipids

Question 18

Predominant in external surface of Phospholipids

Answer 18

phosphatidylcholine and sphingomyelin (with 5% glycolipid)

Question 19

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

Answer 19

Glycolipid

Question 20

Predominant in the internal surface of phospholipids

Answer 20

phosphatidylethanolamine and phosphatidylserine

Question 21

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

Answer 21

Cholesterol

Question 22

Charac of cholesterol

Answer 22

Esterified
Hydrophobic
Equally distributed between the outer and inner layer
evenly distributed within each layer

Question 23

Cholesterol content depends on

Answer 23

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

Question 24

Abnormal L/S ratio

Answer 24

Acanthocyte

Question 25

↑ cholesterol, phospholipids

Answer 25

Codocyte

Question 26

↓ cholesterol

Answer 26

Ovalocyte

Question 27

Cholesterol confers tensile strength to the lipid bilayer

Answer 27

↑ cholesterol → ↑ membrane strength → ↓ elasticity

Question 28

Percentage of carbohydrates

Answer 28

8%

Question 29

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

Answer 29

Glycocalyx

Question 30

Percentage of proteins

Answer 30

52%

Question 31

contains sialic acid which gives RBCs a negative charge

Answer 31

Integral Proteins/Transmembrane Proteins

Question 32

Functions of Integral Proteins/Transmembrane Proteins

Answer 32

Transport site Adhesion site Signaling receptors

Question 33

principal integral CHON

Answer 33

Band 3

Question 34

2 macromolecular complexes of integral proteins:

Answer 34

Ankyrin complex Protein 4.1 complex/Actin junctional complex

Question 35

Major components of ankyrin complex

Answer 35

Band 3 multimers Protein 4.2

Question 36

Major components of Protein 4.1 complex/Actin junctional complex

Answer 36

Band 3 dimers Protein 4.2 Adducin

Question 37

Other transmembrane CHONs

Answer 37

Aquaporin 1 Glut-1 glycophorins Na+, K+-ATPase Ca+2- ATPase blood group antigen ICAM-4

Question 38

🞍 Prevents loss of lipid bilayer 🞍 Provides membrane structural integrity

Answer 38

Integral CHONs + peripheral CHONs

Question 39

principal cytoskeletal CHONs

Answer 39

a-spectrin and β-spectrin

Question 40

Other cytoskeletal CHONs

Answer 40

F-actin (band 5) adducin ankyri dematin tropomodulin tropomyosin

Question 41

Functions of Peripheral Proteins/Cytoskeletal Proteins

Answer 41

Spectrin stabilization Membrane deformation

Question 42

RBC membrane is impermeable to

Answer 42

• Na+ • K+ • Ca2+

Question 43

RBC membrane is permeable to

Answer 43

• H2O • HCO3- • Cl-

Question 44

Transmembrane protein; water transporter

Answer 44

Aquaporin 1

Question 45

What happens when there is a decrease of Aquaporin 1

Answer 45

Hereditary spherocytosis

Question 46

Intracellular (Na: K ratio)

Answer 46

1:12

Question 47

Extracellular (Na: K ratio)

Answer 47

25:1

Question 48

controls active transport of sodium & potassium

Answer 48

Na+, K+ - ATPase

Question 49

↑ Na → water enters the cell →

Answer 49

Cell lysis

Question 50

↑ K →

Answer 50

Cell shrinkage

Question 51

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

Answer 51

Ca2+ - ATPase

Question 52

controls the function of Ca2+ - ATPase

Answer 52

Calmodulin

Question 53

↑ Ca → ↓ membrane stability cell →

Answer 53

cell becomes less deformable

Question 54

Colloid Osmotic Hemolysis:

Answer 54

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