Haematology (The Basics/Physiology)

Question 1

What is the normal concentration of haemoglobin within the red blood cell?

Answer 1

Around 33%- this is the metabolic limit to which a RBC can concentrate haemoglobin.

Question 2

Outline the main precursors, stem cell stages and CFUs of the haematopoienic system.

Answer 2

Question 3

Outline the stages of erythrocyte development

Answer 3

Question 4

EPO:

1. What leads to its increased transcription
2. Which erythroid precursors does it affect

Answer 4

1. Hypoxia inducible factor (HIF-1) which binds to hypoxia. response elements
2. Proerythroblasts onwards.

Question 5

What is the importance of B12 and folate in RBC development?

Answer 5

THey are required in DNA synthesis as they a co-factors in the formation of thymidine triphosphate.

Question 6

Which RBC stage does haemoglobin formation start?

Answer 6

Polychromatophil erythroblasts.

Question 7

How many oxygens are carried by each haemoglobin molecule?

Answer 7

4x.

Question 8

What is the role of hepcidin in iron metabolism?

Answer 8

It is produced in response to increasing iron stores and in inflammation and inhibits cellular iron release from cells.

Question 9

What is the role of hephaestin and ceruloplasmin?

Answer 9

To convert Fe²⁺ to Fe³⁺ which allows its transport.

Haphaestin is a copper dependent enxyme located on the basolateral surface of the enterocyte.

Ceruloplasmin is present on cellular membranes such as macrophages.

Question 10

What is the transport protein that is responsible for iron transport from the enterocyte to plasma?

Answer 10

Ferroportin-1

Question 11

What is the mechanism by which hepcidin reduces the body’s iron stores?

Answer 11

It results in internalisation of ferroportin so that less Fe is absorbed from the intestinal tract.

Question 12

What factors downregulate hepcidin production?

Answer 12

Erythropoiesis (via erythroferrone)

Reduction in bodily iron stores

Question 13

What is the distrubition of total body iron stores?

Answer 13

• 65% as haemoglobin, 1% as other haem compounds
• 15-30% is stored (ferritin)
• 4% myoglobin
• 0.1% travelling as transferritin

Question 14

What stain can be used to evaluate iron stores within bone marrow?

Answer 14

Prussian blue - this stains haemosiderin within macrophages.

Question 15

Which platelet receptors bind to collagen to activate platelets?

Answer 15

The GPI_a/II_a(alpha2-beta1) receptor and the GPVI receptor
This results in GPCR activation of PLC.

Question 16

Which platelet receptor is involved in platelet aggregation?

Answer 16

GP IIb/IIIa

Question 17

Which molecule is produced by platelets and allows activation of certain coagulation factors?

Answer 17

Phosphatidylserine (produced by activated platelets).

Question 18

How is the corrected WBC count performed?

Answer 18

Nucleated count x (100/nRBC + 100)

Question 19

How to correct Rt%

Answer 19

Rt% x (patient PCV/normal PCV)