Haemostasis Flashcards
What are the five steps of haemostasis?
- Vessel spasm
- Platelet plug formation
- Coagulation
- Clot retraction
- Clot dissolution
How does platelet plug formation occur?
Adhesion betwen vWF and GP1B will adhere platelet to exposed collagen, where it will roll over a gp6 causing platelet activation
What occurs within the extrinsic pathway of coagulation?
- Cascade of factors activated via release of tissue factorW
What occurs during the intrinsic pathway?
Platelet activation via thrombin
What happens within the common cascade?
Conversion of prothrombin to thrombin
Which clotting factor will create cross bridges for fibrin?
Factors XIIA
What is created from fibrinolysis?
- D-dimers are formed from the breakdown of fibrin
What are the potential causes for bleeding disorders?
- Missing clotting factors
- Liver disease
- Low platelets
What are the potential causes of thrombosis?
- Insufficient clotting factor inhibitors
- Inappropriate platelet activation
What causes primary haemostasis disorders?
Platelet plug formation issues (thrombocytopenia)
What causes secondary coagulation disorders?
Coagulation problems
What are petechiae bruises?
Any bruise less than 3mm in size
What are purpura bruises?
Any bruise between 3mm - 1cm in size
What are ecchymose bruises?
Any bruise > 1cm
What type of investigations can be used for haemostatic issues
- Full blood counts
- Blood smears
How does asparin work?
Inhibiting production of thromboxane A2
What coloured vacutainer is used for a coagulation assay?
Blue vacutainer as the citrate only tempoerarily inhibits the calcium
What pathway does promthrobin time measure?
Extrinsic pathway
What is a normal time for a prothrombin time assay?
11-16 seconds
What pathway does the Activated partial thromboplastin time assess?
Intrinsic pathway
What is a normal value for activated partial thromboplastin time
30-40 seconds
What pathway does the thrombonin time assess?
Common pathway
What is a normal response time for the thrombonin assay?
15-19 seconds
