Haemostasis Flashcards
Where do platelets come from?
Megakaryocytes in Bone Marrow
How many platelets produced from one cell?
2000-3000
Main hormone in platelet formation
Thrombopoietin
Where is thrombopoietin produced
Mainly liver, also kidney
4 stages of primary haemostatic events
Adhesion, Shape Change, Release Reaction and Aggregation
Adhesion
Injury to vessel wall
Platelets adhere to collagen
VWF binds and recruits
Shape Change
Discoid to spherical
Platelet mono layer
Release Reaction
RBC release granules etc.
Local increase of VWF, fib and FV
Aggregation
More receptors, more recruitment
ADP, thrombin, TXA2 activate platelets
Which factors are Vit K dependent
2, 7, 9, 10
Where are the factors made
the liver
Intrinsic Pathway
Factors 12, 11, 9, 8, 10
TENET
Extrinsic Pathway
Factors 7 and 10
ST. Trauma
Common Pathway
Factors 10, 5, 2, 1, 13
TF TOT
Prothrombin Time (PT)
12-16 seconds
Measures extrinsic and common
Raised PT
Vit K deficiency
Warfarin
Xa or IIa inhibitors
Activated Partial Thromboplastin Time (APTT)
27-35 seconds
Measures intrinsic and common
Raised APTT
Factor deficiency
Lupus coagulant
Haemophilia A
Lowered APTT
Elevated factor VIII
Fibrinogen (Fib)
1.5-4.0g/l
Measures common pathway
Raised Fib
Age
Pregnancy
Contraception
Cancer
Lowered Fib
Liver disease
DIC
Transfusion
Thrombin Time (TT)
13-15 seconds
Measures common pathway
Inherited Raised TT
Deficiency from birth
Dysfibrinogenaemia
Acquired raised TT
DIC
Thrombolytic therapy
Liver disease
