rbc metabolic pathways

GLUT-1

Through what transmembrane protein does glucose penetrate the red blood cell with no energy expenditure?

Transmembrane protein

What type of protein is GLUT-1, which allows glucose to penetrate the red blood cell with no energy expenditure?

Embden-Meyerhof pathway (EMP)

What is the major glycolytic pathway in red blood cells?

90%

What percentage of glucose utilization in red blood cells is handled by the Embden-Meyerhof pathway?

Non-oxidative

Is the Embden-Meyerhof pathway an oxidative or non-oxidative pathway

Anaerobic

Is the Embden-Meyerhof pathway an aerobic or anaerobic pathway

2

How many molecules of ATP are produced by the Embden-Meyerhof pathway

ATP

What energy molecule is used by RBCs for maintenance of shape, active transport of cations, and modulation of 2,3-BPG

Maintenance of RBC shape and deformability

In what way is ATP utilized regarding red blood cell structure and flexibility?

Active transport of cations

In what way is ATP utilized regarding cations in red blood cells

Modulating the amount of 2,3-BPG generated

In what way is ATP utilized regarding 2,3-BPG in red blood cells

Pyruvate kinase (PK) deficiency

What is the most common enzyme deficiency of the Embden-Meyerhof pathway?

HNSHA (Hereditary Nonspherocytic Hemolytic Anemia)

Pyruvate kinase deficiency is the most common form of what type of anemia

Acanthocytes & Burr Cells

What are two possible peripheral blood smear findings in Pyruvate kinase deficiency

PK fluorescent spot test

What is the recommended screening test for Pyruvate kinase deficiency

Autohemolysis test

What secondary screening test evaluates red cell autohemolysis in Pyruvate kinase deficiency

No effect

n the autohemolysis test for Pyruvate kinase deficiency, what effect does the addition of glucose have on autohemolysis

ATP

What substance corrects the greatly increased autohemolysis in Pyruvate kinase deficiency

Type II

What classification type of autohemolysis pattern is associated with Pyruvate kinase deficiency

Quantitative PK assay

What is the confirmatory test for Pyruvate kinase deficiency

3

How many alternate diversion pathways branch from the glycolytic pathway

Hexose-monophosphate shunt, Methemoglobin reductase shunt, Rapoport-Luebering Shunt

What are the three alternate diversion pathways that branch from the glycolytic pathway

Pentose phosphate pathway, phosphogluconate pathway

What are two alternate names for the Hexose Monophosphate Shunt

Aerobic Glycolysis

Is the Hexose Monophosphate Shunt classified as aerobic or anaerobic glycolysis

Pentose

To what sugar does the Hexose Monophosphate Shunt aerobically convert glucose?

NADPH

What reducing molecule is produced when the Hexose Monophosphate Shunt converts glucose to pentose

Glutathione

What compound is reduced by NADPH in the Hexose Monophosphate Shunt

Peroxides

What harmful oxidative molecules are reduced by reduced glutathione

proteins, lipids, and heme iron

What three RBC structures or components are guarded from oxidation by reduced glutathione

Globin portion

What specific portion of hemoglobin is protected from oxidation by reduced glutathione

G6PD

The functionality of the Hexose Monophosphate Shunt is dependent on what enzyme^[5]

Denaturation of the globin by oxidation

What process affecting globin is prevented by the Hexose Monophosphate Shunt^[5]

G6PD deficiency

What is the most common enzyme deficiency in the pentose phosphate pathway?

G6PD deficiency

What is the most common RBC enzyme defect overall

5%

What percentage of the global population is estimated to be affected by G6PD deficiency

400 million

Approximately how many people worldwide are affected by G6PD deficiency

Heinz bodies and Bite cells

What two possible peripheral blood smear findings are associated with G6PD deficiency

G6PD fluorescent spot test

What is the recommended screening test for G6PD deficiency

Autohemolysis test

What secondary screening test evaluates red cell hemolysis patterns in G6PD deficiency

Slightly to moderately increased

How is the degree of autohemolysis described in G6PD deficiency

Glucose

What substance partially corrects autohemolysis in G6PD deficiency

Type I

What classification type of autohemolysis pattern is associated with G6PD deficiency

Quantitative G6PD assay

What is the confirmatory test for G6PD deficiency

Severely deficient <1% activity or not detectable

What is the G6PD enzyme activity level in Class I G6PD deficiency

Chronic, HNSHA

What are the clinical manifestations of Class I G6PD deficiency

G6PD-Serres, G6PD-Madrid

What are two examples of Class I G6PD deficiency variants

Severely deficient <10%

What is the G6PD enzyme activity level in Class II G6PD deficiency

Infections, certain drugs, and fava beans

What triggers severe, episodic acute hemolytic anemia in Class II G6PD deficiency

Not self-limited

Is the acute hemolytic anemia in Class II G6PD deficiency self-limited

Transfusions

What medical intervention may be required during hemolytic episodes in Class II G6PD deficiency

Favism

What term defines unusual sensitivity to fava beans

G6PD-Mediterranean

Most G6PD-deficient individuals who demonstrate favism possess which specific variant

G6PDMediterranean, G6PDChatham

What are two examples of Class II G6PD deficiency variants

Mild to moderately Deficient 10-60% activity

What is the G6PD enzyme activity level in Class III G6PD deficiency

Self-limited

Is acute hemolytic anemia in Class III G6PD deficiency self-limited

G6PD-A, G6PD-Canton

What are two examples of Class III G6PD deficiency variants

Mild deficient to Normal 60-150% activity

What is the G6PD enzyme activity level in Class IV G6PD deficiency

None

What are the clinical manifestations of Class IV G6PD deficiency

G6PD-B

What is the wildtype variant of G6PD in Class IV

G6PD-A+

Which Class IV G6PD variant may also manifest as Class II

Increased >150% activity^[11]

What is the G6PD enzyme activity level in Class V G6PD deficiency

none

What are the clinical manifestations of Class V G6PD deficiency

Ferrous (2+) to ferric (3+)

Peroxide oxidizes heme iron from which state to which state

Methemoglobin

What is hemoglobin called when its iron is oxidized to the ferric (3+) state

Cytochrome b5 reductase

What is an alternate name for methemoglobin reductase

Conversion of G3P

Cytochrome b5 reductase uses H+ from NADH generated during which enzymatic step

More than 65%

What percentage of methemoglobin-reducing capacity in the RBC is accounted for by cytochrome b5 reductase

Production of 2,3-BPG

What is the primary function of the Rapoport-Luebering Shunt

Decreases

What effect does 2,3-BPG binding have on hemoglobin's affinity for oxygen

Partial pressure

What are the two main variables plotted on the oxygen dissociation curve

Bohr effect

What term describes a shift in the oxygen dissociation curve due to an alteration in pH or hydrogen ion concentration

Haldane effect

What term describes the phenomenon where O2 binding to hemoglobin promotes CO2 release

Increased pH

What changes in pH, pCO2, 2,3-BPG, and temperature cause a SHIFT TO THE LEFT in the oxygen dissociation curve

Increased

Does a SHIFT TO THE LEFT result in increased or decreased oxygen affinity

Decreased pH

What changes in pH, pCO2, 2,3-BPG, and temperature cause a SHIFT TO THE RIGHT in the oxygen dissociation curve

Decreased

Does a SHIFT TO THE RIGHT result in increased or decreased oxygen affinity?