RBC Metabolism/Destruction

Question 1

What is the Embden-Meyerhof Pathway?

Answer 1

An anaerobic pathway – glucose the sole substrate of the RBC is converted to lactate; net product of 2 ATP i think

Question 2

What are Heinz bodies?

Answer 2

Insoluble precipitates formed when damaged/denatured Hb rapidly accumulates

Question 3

What is the major source of energy for RBCs?

Answer 3

ATP (from glucose)
note: ATP maintains cell volume, shape & flexibility

Question 4

What occurs when someone has a Glucose-6-phosphate dehydrogenase deficiency?

Answer 4

• G6PD reduce NADP and is the only source of NADPH.
• NADPH is needed to reduce glutathione
• If they are deficient then they will be unable to produce glutathione which protects the RBCs from oxidative stress.
• Therefore, if the person is under oxidative stress this will result in acute haemolytic anaemia.

Question 5

What happens when the enzyme present in an RBC is imperfect?

Answer 5

The RBC won’t be able to compensate bcuz it is unable to produce new enzymes to replace the bad ones. This means the RBC will be destroyed (hemolysis).
The enzymes carry out the metabolic processes.

Question 6

What happens when someone has a pyruvate kinase deficiency?

Answer 6

They will be unable to generate the ATP required to maintain the membrane integrity of the RBC. Therefore, the RBC will be destroyed (hemolysis).

Question 7

Breakdown of haem results in what?

Answer 7

iron (for recirculation) and protoporphyrin (which is broken down into bilirubin)

Question 8

Where do red cells die?

Answer 8

In the spleen or liver (RBCS removed extravascularly by the macrophages of the RE system)

Question 9

Globin chains are broken down into what?

Answer 9

Amino acids (reutilized for protein synthesis)

Question 10

What is haptoglobin?

Answer 10

Protein that binds to haemoglobin that is circulating freely in the blood. The haptoglobin-haemoglobin complex is removed the RE system. Thats why when you have haemolytic anaemia there is a decrease in haptoglobin bcuz most of it is being used up, then removed.

Question 11

Acute haemolytic anaemia as a result of G6PD deficiency is caused by?

Answer 11

• Oxidant stress eg. from drugs, fava beans or infections. - The acute haemolytic anaemia is caused by rapidly developing intravascular haemolysis with haemoglobinuria.
• The anaemia may be self‐limiting

Question 12

A rise in 2,3-DPG cause what?

Answer 12

• A decrease of oxygen affinity and the O2 curve shifts to the right.
• note when O2 is unloaded from Hb, the 2,3-DPG is allowed to enter

Question 13

The ability of the RBC to deform (flexible) is dependent on the integrity of its membrane. T or F.

Answer 13

T
note: relies on the RBC’s to generate energy as ATP & NAPH

Question 14

What is NADPH used for (from the EMB glycolytic pathway)?

Answer 14

NADH is used by methaemoglobin reductase to reduce functionally dead methaemoglobin (oxidized Hb/Fe3+) to functionally active, reduced Hb (Fe2+).

Question 15

What is the Rapaport-Luebering Shunt?

Answer 15

generates 2,3 Diphosphoglyceric acid (2,3,DPG) which when bound to Hb, decreases its affinity for Oxygen leading to Oxygen delivery to tissues

Question 16

whats the Hexose monophosphate shunt (HMP)?

Answer 16

• it produces gluthatione, a reducing agent that protects RBCs from oxdative damage
• G6PD produces NADP while oxidizing glucose-6-phosphate
• NADPH is needed to reduce glutathione so it can do its job

Question 17

At which two stages is ATP produced in the EM glycolytic pathway?

Answer 17

• 2,3 DPG to 3-phosphogylcerate
• Phosphoenol pyruvate to pyruvate

Question 18

what happens to the cell density of aged cells?

Answer 18

it increases

Question 19

occurance of random hemolysis?

Answer 19

<0.5 %