Haemostasis and coagulation Flashcards
What is thrombosis
Formation of unwanted clots
What is the intrinsic clotting mechanism
Exposed collaged from injured blood vessel wall, test tube
What is the extrinsic clotting mechanism
Damaged tissue releases thromboplastin
What is the amplification cascade
1) Foreign substance in body
2) intrinsic clotting mechanism forms clotting factors
3) Extrinsic clotting mechanism releases thromboplastin
4) thromboplastin and clotting factors come together to turn Inactive X to Active X
5) Active X chops up prothrombin to thrombin which acts as an enzyme
6) Thrombin turns fibrinogen to fibrin which acts as a scaffold and forms blood clots
What is fibrinogen a risk factor for
CVD which means that there is an increase in the formation of clots
What reactions are platelets part of
Adhesion
Aggregation
What is the adhesion reaction like for platelets
Adhere to sub endothelial surface on damage/disease due to Von WIllebrand’s factor
What is the aggregation reaction like for platelets
Adhesion causes release reaction
- ADP and thromboxane promote platelet aggregation
- Leads to platelet mass to plug area of endothelial damage which promotes the coagulation reaction
What is coagulation involved in
Homeostasis- stops blood loss through damaged vessels
What tests are there to test blood
- Bleeding time
- INR
What is bleeding time
-What causes an increased bleeding time
Incision in arm
-Platelet dysfunction
What Is INR
Time for coagulation follow addition of thromboplastin
Why are venous clots formed and what may they cause
Clots form in veins because of stasis of blood
-May cause pulmonary embolism
What risk is there for atrial fibrillation
Risk of ischaemic attack (stroke)
Where do arterial thromboses form
Atherosclerotic sites
What do arterial thromboses lead to
Arterial blockages which would lead to
- Heart attack
- Stroke
How would atrial fibrillation lead to a cardioembolic stroke
If a clot forms in the left atria, it can break off and go to the brain
What causes a pulmonary embolism
If clot is in right atrium
What is venous thrombosis more caused. by
Coagulation factors (so would lead to DVTs)
What are arterial thromboses more caused by
Platelets (so would lead to MIs and ischaemic strokes)
What causes haemophilia A
Genetic cause- Carried on X chromosome so males are most affected and females are carriers
What causes the symptoms of haemophilia A
Low or lacking Factor 8 of the clotting cascade
What are the symptoms of haemophilia A
Haemorrhage and prolonged bleeding
How to treat haemophilia A
Treat with factor 8 from blood donors
-Emicizumab (monthly injections)
