Blood clotting Flashcards
(11 cards)
What are the five key steps in blood clotting?
- Vessel spasm, 2. Platelet activation and aggregation, 3. Coagulation cascade, 4. Clot retraction, 5. Clot dissolution (fibrinolysis).
Why are platelets important in blood clotting?
Platelets adhere to collagen at the injury site, become activated, release granules (e.g., ADP), synthesize TXA₂, and form a temporary platelet plug.
What distinguishes the intrinsic from the extrinsic clotting pathway?
Intrinsic pathway is slower and activated by trauma inside the vascular system; extrinsic is faster, initiated by external trauma that causes blood to escape the vessel.
What is the role of thrombin in clotting?
Thrombin converts fibrinogen into fibrin, which forms a mesh to stabilize the platelet plug into a clot.
What is clot retraction?
A post-clotting event where platelets contract, pulling the wound edges together and squeezing out serum to aid healing.
What is fibrinolysis?
The process of breaking down a blood clot after vessel repair, primarily through the enzyme plasmin, regulated by activators and inhibitors.
How is platelet activation negatively regulated?
By healthy endothelium releasing prostacyclin (PGI₂) and nitric oxide (NO) to prevent unnecessary platelet activation.
What are common diseases associated with excessive blood clotting?
Arterial thrombosis (e.g. MI, stroke), venous thrombosis (e.g. DVT); both can lead to embolism and serious complications.
How are thrombotic conditions treated?
Arterial: antiplatelet drugs (aspirin, clopidogrel); Venous: anticoagulants (warfarin); Clot dissolution: fibrinolytics (t-PA, alteplase).
What conditions lead to insufficient clotting?
Thrombocytopenia, impaired clotting factor synthesis (e.g. liver disease), and hereditary disorders like haemophilia A and von Willebrand disease.
What are some treatments for bleeding disorders?
Platelet or clotting factor infusions depending on the underlying deficiency or disorder.
