Erythrocyte Metabolism

Question 1

RBC relies on _____________ for its energy.

Answer 1

anaerobic glycolysis

Question 2

Two sites on the Hgb molecule which are prone to oxidation:

Answer 2

Iron atom (heme)
Sulfhydryl groups (globin)

Question 3

RBC metabolic processes requiring energy:

Answer 3

• Intracellular cationic gradient maintenance
• Maintenance of membrane phospholipid distribution
• Maintenance of skeletal protein deformability
• Maintenance of functional hemoglobin with ferrous iron
• Protecting cell proteins from oxidative denaturation
• Glycolysis initiation and maintenance
• Glutathione synthesis
• Nucleotide salvage reactions

Question 4

principal source of energy

Answer 4

Glucose

Question 5

Other sources of energy:

Answer 5

Galactose
Fructose
Mannose

Question 6

RBC membrane is permeable to

Answer 6

Glucose

Question 7

RBC membrane is impermeable to

Answer 7

Sucrose
Lactose
Maltose

Question 8

Percentage of glucose metabolized by the Embden-Meyerhof pathway (EMP)

Answer 8

90-95%

Question 9

Percentage of glucose metabolized by the Hexose Monophosphate Shunt (HMP)/Pentose Phosphate Shunt (PPS)

Answer 9

5-10%

Question 10

Main methabolic pathway in RBC

Answer 10

Embden-Meyerhof Pathway

Question 11

Major source of RBC energy | 90% Anaerobic glycolysis

Answer 11

Embden-Meyerhof Pathway

Question 12

Embden-Meyerhof Pathway requires _________ for energy production

Answer 12

Glucose

Question 13

EMP Maintains cellular energy by generating

Answer 13

2 ATP molecules

Question 14

most common deficiency in the E-M pathway

Answer 14

PK (Pyruvate kinase) deficiency

Question 15

Rate of glycolysis:

Answer 15

• ↑ when there is ↑ in the
intracellular pH (hypoxia)
• ↓ when ATP levels ↑ and
vice versa

Question 16

• Maintains membrane proteins & lipids, enzymes, hemoglobin iron in its ferrous state
• Prevents denaturation of Hb molecule by oxidation

Answer 16

Hexose Monophosphate Shunt/ Oxidative Pathway/
Pentose-Phosphate Pathway

Question 17

G6PD → NADP is reduced to NADPH → converts oxidized glutathione (GSSG) to reduced
Glutathione (GSH) in the presence of

Answer 17

glutathione reductase

Question 18

Reduced Glutathione reduces ________ to H20 + 02 by glutathione peroxidase

Answer 18

Peroxide

Question 19

(most common inherited RBC enzyme
worldwide) → denatured globins → Heinz bodies

Answer 19

G6PD deficiency

Question 20

provides the only means
of generating NADPH

Answer 20

G6PD

Question 21

Long term oxidation

Answer 21

Hexose Monophosphate Shunt/ Oxidative Pathway/
Pentose-Phosphate Pathway

Question 22

Peroxide oxidizes heme iron [(ferrous (+2) → ferric (+3)] = Peroxide oxidizes heme iron [(ferrous (+2) → ferric (+3)] =

Answer 22

methemoglobin (unable to carry O2)

Question 23

Maintenance of the iron in its FERROUS state by

Answer 23

methemoglobin reductase/cytochrome b5 reductase

Question 24

NADPH in the presence of ____________converts ferric iron → ferrous iron

Answer 24

methemoglobin reductase

Question 25

Short term effect

Answer 25

Methemoglobin Reductase Pathway

Question 26

Last diversion pathway
Generates 2,3 DPG w/c regulates O2 delivery to tissues by competing w/ O2 for the O2 binding
site of Hb

Answer 26

Rapoport-Luebering Pathway

Question 27

↑ 2,3-BPG: ↓ Hb affinity to O2 →

Answer 27

↑ Tissue oxygenation

Question 28

↓ 2,3-BPG: ↑ Hb affinity to O2 →

Answer 28

↓ Tissue oxygenation

Question 29

Loc of ↑ Tissue oxygenation

Answer 29

Tissues

Question 30

Loc of ↓ Tissue oxygenation

Answer 30

Lungs