Studied by 2 people
Looks like no one added any tags here yet for you.
What elements does the haemostatic response have?
Vasoconstriction
Platelet adhesion and aggregation
Clotting - coagulation phase
What is the size and appearance of a platelet?
2-3 widemetre
Small, over, no nucleus
What do platelets contain/ how are they made?
granules
megakaryocyte cytoplasm (fragments into platelets)
What is platelet production controlled by?
No of circulating platelets (negative feedback)
Thrombopoietin release
What is the normal lifespan of platelets?
7-10 days
What 3 things does a vessel injury trigger
Vasoconstriction
Collagen exposure
Tissue factor
What is the pathway to a primary haemostatic plug?
Vasoconstriction (+ seratonin from platelet activation) - reduced blood flow
Collagen exposure → platelet adhesion → platelet activation → thromboxane → platelet activation
Primary haemostatic plug
What does platelet activation entail ?
Shape change
Granule secretion
Activation GPIIb/IIa
How is the stable haemostatic plug produced?
Tissue factor → blood coagulation cascade → thrombin → fibrin
How is soluble plasma converted to insoluble rigid fibrin?
Fibrinogen → Fibrin
Enzyme Thrombin
Factor XIII stabilises fibrin
What factor stabilises fibrin?
XIII
What is the Extrinsic pathway?
Initiation of coagulation
Tissue factor binds to FVII → Tissue Factor-FVIIa complex
Binds to FX and activated it to become FXa
What factors are involved in the extrinsic pathway?
Tissue factor
FVII
Tissue factor FVIIa complex
FX
FXa
What is the intrinsic pathways of the coagulation phase?
Factor IX and co-factor VIII
Activates FX - Fxa
More slowly than extrinsic pathway
Which is faster, the intrinsic or extrinsic coagulation phase?
Instrinsic phase
What factors are involved in the intrinsic pathway?
Factor IX and co-factor VIII
FX and FXa
What is the common pathway of the coagulation phase?
Prothrombinase (FXa and FVa as a co-factor)
Activated prothrombin → THROMBIN
THROMBIN converts FIBRINOGEN → FIBRIN
What vitamins and minerals do you need for bloodclotting?
Calcium and vitamin K
What is vitamin K necessary for?
Certain clotting factors in the liver including prothrombin
What natural ‘anticoagulants’ are there in normal plasma?
Antithrombin - inhibits thrombin
Heparin - released by basophils and mast cells - co-factor that accelerated actions of Antithrombin
How many blood group systems are there?
35
What differentiates blood groups?
Antigens on red blood cell membrane
What are the blood groups with the most clinical significance?
ABO and Rh(D) blood group systems
What antigens and antibodies does someone with Group A blood group have?
A antigen on RBC, Anti-B antibodies in plasma
Which blood groups are dominant and recessive?
A + B = dominant
O = recessive
What is Rh+ or - determined by?
Presence of the D antigen
Does a Rh (-) individual contain anti-Rh(D) antibodies?
Not usually
What is required for the presence of anti-Rh(D) antibodies?
Sensitisation by exposure to Rh+ RBCs
What would cause Haemolytic disease of a newborn?
Rh negative mother and Rh positive baby
What do you transfuse in an emergency?
transfuse with O Rhesus negative: universal donor
