Haemotology

Question 1

What are the three main contributors to haemostasis?

Answer 1

The blood vessels

The platelets

The coagulation factors (soluble plasma proteins)

Question 2

What are the phases of the haemostatic mechanism?

Answer 2

Primary haemostasis, secondary haemostasis, and fibrinolysis.

Question 3

What are the three layers of the blood vessel wall and their function?

Answer 3

1- Intima (inner layer),
compromised of endothelial cells

2- media (smooth muscle layer)
regulates vascular tone

3- and adventitia (outer layer).
compromised of collagen and fibroblasts

Question 4

Normal platelet count and their life span?

Answer 4

150–400 x 10⁹/L.
7–10 days.

Question 5

What stimulates platelet production?

Answer 5

Thrombopoietin (TPO).
Produced by liver

Question 6

What are the three types of granules in platelets and what do they contain?

Answer 6

α-granules - fibrinogen, vWF, coagulation factors, P selectin

dense granules - ADP, ATP, Calcium, serotonin

lysosomes- collagenase, elastase, hydrolytic enzymes

Question 7

What role do platelets play in haemostasis?

Answer 7

They adhere to injured endothelium, activate, aggregate, and form a platelet plug.

Question 8

What prevents platelet activation in healthy vessels?

Answer 8

Endothelial cells release nitric oxide, prostacyclin, and CD39

Question 9

What triggers platelet activation in damaged blood vessels

Answer 9

Damaged endothelium causes exposure of extracellular matrix proteins like collagen.

Question 10

What is the process of thrombopoiesis.

Answer 10

Occurs in 2 phases.
Phase 1- Endomitosis (DNA replication without cell division)
Cytoplasm enlargement (cytoskeletal proteins and platelet granules)
Mature megakaryocytes extend long branching processes (proplatelets)
Organelles and granules are transported to proplatelets
Driven by cytoskeletal rearrangements