7. Erythrocytes - Grossclose

Question 1

Define the term erythron

Answer 1

circulating red blood cells, their precursors, and the tissues that produce them

Question 2

Define the term reticulocyte.

Answer 2

A young erythrocyte that contains no nucleus but has residual RNA

Question 3

Define the term anemia.

Answer 3

reduction below normal of the number of erythrocytes, quantity of hemoglobin, or the volume of packed red cells in the blood

Question 4

Name the hormone that triggers differentiation of stem cells into red cells.
Where is it synthesized? What stimulus provokes its release?

Answer 4

Erythropoietin; synthesized in the kidney and liver.

Question 5

What are the ABH antigens? What are the products of the ABH genes?

Answer 5

ABH antigens are immunodominant sugars added to chains of N-acetylgalactosamine, galactose and fucose to form type A, B, and O blood types.

Question 6

[TQ] What’s so special about the red cell’s shape?

Answer 6

The red cell’s shape has the maximize ratio of surface area to volume, while preventing blood flow impedement.

Question 7

By what organs are red cells normally removed from the circulation, and at what red cell age?

Answer 7

The spleen removes RBC from circulation when they hit around 120 days (old).

Question 8

Name 3 major metabolic capabilities that red cells LACK.

Answer 8

citric acid cycle
protein synthesis
oxidative phosphorylation
heme synthesis

Question 9

How is G-6-P dh deficiency usually first observed in a patient?

Answer 9

hemolysis of RBC

Question 10

How does 2,3-BPG affect hemoglobin function?

Answer 10

Synthesized in erythrocytes, 2,3-BPG binds to the cleft between the deoxy hemoglobins to improve oxygen delivery, allowing for skipping the kinase activity.

Question 11

[TQ?] Describe how membrane band 3 complex acts as an oxygen sensor to vary the activities of glycolysis and the pentose phosphate pathway.

Answer 11

Some enzymes of the glycolytic pathway, associate and disassociate with Band 3 complex, and that depends on whether the hemoglobin is oxygenated or non oxygenated.

Ex. Aldolase and G3PD associate/bind to Band 3 when there is a lack of deoxy Hb), causing a production of NADPH via PPP. When [O2] decreases and [deoxy Hb] increases, the enzymes unbind, allowing for the glycolytic pathway, to produce ATP and NADH.

Question 12

Name as many causes of anemia as you can.

Answer 12

Anemia caused by blood loss (ulcer, menstruation)

Anemia caused by decreased or faulty red blood cell production. (via vitamin deficiency - B12 and folate)

Anemia caused by destruction of red blood cells (Glucose 6-Phosphate dehydrogenase deficiency and Pyruvate kinase deficiency)

Question 13

What is the source of the CO2 produced by red cells?

Answer 13

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