10 - thrombosis

Question 1

Haemostasis is the balance between which 2 systems?

Answer 1

• fibrinolytic factors and anticoagulant proteins
  (stop clotting inappropriately/prematurely)
• coagulation factors and platelets
  (forces of clotting)

Question 2

What is thrombocytopenia?

Answer 2

a relative decrease in the number of platelets in the blood

Question 3

When you damage the endothelial cell wall, collagen and tissue factor are exposed. There are the 2 triggers for haemostasis.

Answer 3

collagen - trigger for primary haemostasis

TF - trigger for secondary haemostasis

Question 4

How is fibrin produced and how does it act on platelets?

Answer 4

thrombin converts fibrinogen into firbin, which forms an insoluble mesh around the platelets

Question 5

What what causes haemophilia?

Answer 5

The failure to generate fibrin to stabilise the platelet plug. This is due to lack of factor 8 or 9, hence thrombin is not produced.
You are left with only a primary platelet plug that is not stabilised. (this can be ok in smaller vessels, but will be destroyed in bigger vessels)

Question 6

What is haemarthrosis?

Answer 6

bleeding into the joints

a hallmark of haemophilia (A and B)

Question 7

What are the effects of thrombosis?

Answer 7

• obstructed flow of bloo
• —-> artery - MI, stroke, limb ischaemia
• —-> vein - pain and swelling
• embolism
• —-> venous - pulmonary embolism
• —-> artertial - usually from the heart

Question 8

What are the 3 contributory factors of thrombosis? (Virchow’s triad)

Answer 8

BLOOD (thickness)
- deficiency of anticoagulant proteins e.g. antithrombin, protein C, protein S
- increase in coagulant proteins/activity e.g. factor 8, factor 2, Factor 5 leiden, thrombocytosis
VESSEL WALL
expression of proteins involved in coagulation are altered in inflammation (thrombomodulin is down regulated)
FLOW
reduced flow (stasis) increases risk of venous thrombosis