Ch. 9 - Energy Metabolism and Membrane Physiology of the Erythrocyte

Question 0

Process that provides energy to the RBCs

Answer 0

Glycolysis

Question 1

Average life span of RBCs

Answer 1

120 days

Question 2

Disease where there is shortened RBC survival due to deficiencies in enzymes involved in glycolysis

Answer 2

Hereditary nonspherocytic hemolytic anemia

Question 3

What are the intracellular levels sodium, potassium and calcium?

Answer 3

• Low sodium and calcium

- high potassium

Question 4

What are the extracellular levels of sodium, calcium and potassium?

Answer 4

• low potassium

- high sodium and calcium

Question 5

Main molecule that supplies the energy of RBCs

Answer 5

Glucose

Question 6

What is the net gain of ATP with the Embden-Meyerhof pathway?

Answer 6

2 molecules of ATP

Question 7

3 shunts/diversions in the glycolytic pathway to generate products that maximize oxygen delivery from several vantage points

Answer 7

• Hexose monophosphate pathway (HMP)/aerobic glycolysis/pentose phosphate shunt
• Methemoglobin reductase pathway
• Rapoport-Leubering pathway

Question 8

What generally happens in the Hexose monophosphate pathway?

Answer 8

There is synthesis of glutathione that will reduce peroxide to water and oxygen. By detoxifying peroxide, the functional life span of the RBC is increased.

Question 9

Molecule that is an essential requirement in the hexose monophosphate pathway. Without it, erythrocytes are vulnerable to oxidative reduction.

Answer 9

Glucose-6-phosphate dehydrogenase

Question 10

What is the general purpose of the methemoglobin reductase pathway?

Answer 10

The pathway makes sure that the iron must be in the ferrous state to participate in the formation of heme.

Question 11

What happens during the Rapoport-Leubering pathway?

Answer 11

2,3-bisphosphoglycerate regulates oxygen delivery to tissues by competing with oxygen for hemoglobin. Oxygen is released when 2,3-BPG binds which enhances delivery of oxygen to the tissues.

Question 12

3 factors that affect RBC deformability

Answer 12

• geometry
• viscosity
• elasticity/plasticity/pliancy

Question 13

Average volume of RBCs

Answer 13

90 fL

Question 14

Average surface area of RBCs

Answer 14

140 um2

Question 15

How many time can the RBCs be stretched without damage?

Answer 15

2.5 times their resting diameter

Question 16

Normal range of mean cell hemoglobin concentration

Answer 16

32-36%

Question 17

What is the relationship between hemoglobin concentration and viscosity?

Answer 17

Directly proportional; as hemoglobin concentration increases, viscosity rises

Question 18

What are the percent composition of carbohydrates, proteins and lipids in the RBC membrane?

Answer 18

• 8% carbohydrates
• 52% proteins
• 40% lipids

Question 19

Substances in the RBC membrane that reseals tears when the membrane is torn

Answer 19

Phospholipids

Question 20

Substance in the RBC membrane that confers tensile strength to the lipid bilayer

Answer 20

Cholesterol

Question 21

Substance that maintains the cholesterol concentration in the lipid bilayer by regularly exchanging membrane and plasma cholesterol

Answer 21

Membrane enzymes

Question 22

2 phospholipids on the outer layer of the RBC membrane

Answer 22

• Phosphatidylcholine

- Sphingomyelin

Question 23

2 phospholipids in the inner layer of the RBC membrane

Answer 23

• Phosphatidylserine (PS)

- Phosphatidylethanolamine

Question 24

The only negatively-charged phospholipid

Answer 24

Phosphatidylserine

Question 25

Phospholipid that redistributes (flips) to the outer layer during sickle cell anemia & thalassemia or in RBCs that have reached their 120 day life span

Answer 25

Phosphatidylserine

Question 26

When does the "target cell" appearance of RBCs occur?

Answer 26

When there is low bile salt concentration which in turn lowers membrane cholesterol concentration

Question 27

A layer of carbohydrates whose net negative charge prevents microbial attack and protects the RBC from mechanical damage caused by adhesion to the neighboring RBCs or to the endothelium

Answer 27

Glycocalyx

Question 28

The glycocalyx is made up of ____________

Answer 28

Glycolipids

Question 29

Aggregation of transmembranous proteins that provide RBC membrane structural integrity

Answer 29

Ankyrin/protein 4.1

Question 30

The transmembranous proteins provide _________ membrane structure

Answer 30

Vertical

Question 31

What is used to stain glycophorins?

Answer 31

Periodic-acid Schiff (PAS) dye

Question 32

Indentification technique that distinguished 15 membrane proteins

Answer 32

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) using Coomassie blue dye

Question 33

2 principal skeletal proteins

Answer 33

Alpha-spectrin and beta-spectrin

Question 34

Shape formed by the spectrins

Answer 34

Hexagonal lattice

Question 35

How many triple helix repeats make up an alpha spectrin?

Answer 35

20 triple-helical repeats with 106 amino acids each

Question 36

How many triple helix repeats make up a beta-spectrin?

Answer 36

16 triple-helical repeats of 106 amino acids each

Question 37

Condition where the RBC membrane fails to rebound from deformation, and the RBCs progressively elongate to form visible eliptocytes which cause a mild to severe hemolytic anemia

Answer 37

Hereditary elliptocytosis (ovalocytosis)

Question 38

A transmembranous protein that forms spores or channels whose surface charges create inward flow of water in response to internal osmotic changes

Answer 38

Aquaporin 1

Question 39

A transmembranous protein that transports glucose without energy expenditure

Answer 39

Glut-1

Question 40

Intracellular-to-extracellular ratio sodium

Answer 40

1:12

Question 41

Intracellular-to-extracellular ratio of potassium

Answer 41

25:1

Question 42

Normal range of calcium intracellularly

Answer 42

5-10 umol/L

Question 43

Enzyme that increases the reduction rate of methemoglobin by NADPH

Answer 43

Cytochrome b5 reductase (cytob5r)

Question 44

Regulates the concentration of Na and K, maintaining the normal intracellular-extracellular ratios

Answer 44

ATPase-dependent cation pumps

Question 45

Condition where there is pump mechanism damage which permits the influx of Na, with water following osmotically. The cell swells, becomes spheroid, and eventually ruptures

Answer 45

Colloid osmotic hemolysis

Question 46

Mechanism that extrudes Ca from the RBC

Answer 46

Ca2+ ATPase

Question 47

Controls the function of Ca2+ ATPase; a cytoplasmic Ca2+­binding protein

Answer 47

Calmodulin