Haemostasis and Blood Groups Flashcards
What is haemostasis?
Stopping bleeding. It is a balanced interaction of blood cells, vasculature, plasma proteins and low molecular weight substances
What does perfect haemostasis mean?
No bleeding and no thrombosis.
What is primary haemostasis?
Temporary platelet plug
What is secondary haemostasis?
Coagulation and stable clot.
What is vascular spasm and what is it triggered by?
Prompt constriction of a broken vessel triggered by pain receptors, injury to smooth muscle and platelet releasing serotonin.
How is a platelet plug formed?
Platelets stick to exposed collagen and other platelets whilst releasing ADP.
Platelet plug formation is an example of what type of feedback cycle?
Positive feedback
What happens during coagulation?
Clotting factors in plasma. Thrombin causes fibrinogen to turn to fibrin.
There are two pathways for coagulation, extrinsic and intrinsic. Which one is faster?
Extrinsic.
Which clotting factor stabilises fibrin?
Factor XIII
How does the blood clot dissolve (fibrinolysis)?
By plasmin, a fibrin-dissolving enzyme or clot buster
Which natural anticoagulants are present in the blood?
Antithrombin produced by the liver and heparin secreted by basophils and mast cells
Wow do anticoagulants work?
They block the action of thrombin to prevent fibrinogen converting to fibrin.
What are the 4 main blood group types?
O, A, B and AB
What do the antigens on blood cells determine?
The blood group
