Haemostasis Flashcards
(29 cards)
Define Haemostasis and state 2 functions
What are the 3 steps in Haemostasis
The stopping of bleeding
Prevents bleeding
Prevents unnecessary coagulation
Make clot
Control clotting
Breakdown of clot (Fibrinolysis)
What 5 things are essential for Haemostasis
Keep blood moving Blood vessels Platelets Coagulation factors Anticoagulant factors
Compare primary and secondary Haemostasis
Primary: Platelets aggregate to form a plug at the vessel hole
Secondary: Plug strengthened with fibrin filaments
Describe Platelet Adhesion
- Damage to vessel wall
- Exposure of underlying tissues
- Platelets adhere to collagen via vWF receptor
Describe platelet activation
- Platelets secrete ADP and other substances to become activated and activate other platelets
- Involved in activation of clotting cascade
- Secrete coagulation factors from internal stores
Describe Platelet Aggregation
Cross linking of platelets to form a platelet plug
Identify 7 mediating factors that stimulate clotting
Platelet receptors- Glycoprotein complexes Von willebrands factor Fibrinogen Collagen surfaces ADP Thrombin Thromboxane
Outline the clotting cascade mechanism to make fibrin
- Intrinsic and extrinsic pathways activate Factor X
- Factor Xa activates Prothrombin II-> Thrombin IIa
- Thrombin IIa activates Fibrinogen 1-> Fibrin Ia
What are 2 ways that coagulation is controlled
- Natural anticoagulants inhibit activation of clotting cascade
- Clot destroying proteins, which are activated by the clotting cascade
Name 4 Natural Anticoagulants
Protein C
Protein S
Antithrombin
Tissue factor pathway inhibitor
What are Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT)
PT: A diagnostic test used to evaluate the extrinsic and common pathway
APTT: A diagnostic test used to evaluate the intrinsic and common pathways
A problem with which factors cause Prolonged PT
Which pathways are each factor in
7- Extrinsic
5,10,Prothrombin, Fibrinogen- Common
A problem with which factors cause Prolonged APPT
Which pathways are each factor in
8,9,11,12- Intrinsic pathway
5,10, Prothrombin, Fibrinogen- Common Pathway
What are D dimers
Fibrin degradation products
What does Von Willebrand Factor do
Involved in;
- Platelet aggregation
- Platelet adhesion
- Carries factor 8
What are 3 functions of the vessel wall
- Vasoconstriction
- Production of Von Willebrand’s Factor
- Exposure of collagen and tissue factor, initiating activation of clotting factors
Outline fibrinolysis
Plasminogen activator activates PLASMIN from PLASMINOGEN
Plasmin breaks down FIBRIN to D-Dimers
What are 3 causes of bleeding disorders and what are the 2 types
Inherited and acquired
Abnormalities in;
- Vessel wall
- Platelets
- Coagulation factors
What are 2 types of Coagulative Disorders
Congenital and acquired
Identify 3 congenital coagulation factor disorders
Identify 3 acquired coagulation factor disorders
Haemophilia A ( Deficiency in factor 8) Haemophilia B (Deficiency in factor 9) Von Willebrand’s disease
Liver disease
Vit K deficiency (Causes more bleeding)
Anticoagulants
Identify 4 signs of Coagulation factor disorders
- Intercerebral haemorrhage
- Severe post op, post traumatic bleeding
- Joint pain and deformity
- Prolonged bleeding after dental extraction
What is the inheritance pattern for Haemophilia
How does it present
How is it treated
X-linked recessive
Bleeding into muscles and joints, and post-operatively
Treated with recombinant factor 8 or DDAVP (releases factor 8 from vessels)
What is the inheritance pattern for Von Willebrand’s Disease
Identify 2 signs
What is the main genetic defect
Autosomal dominant
- Abnormal platelet adhesion to vessel wall
- Reduced Factor 8 amount/ activity
Main: Reduced vWF production
What are 3 clinical signs of von Willebrand’s Disease
Skin and mucous membrane bleeding
Prolonged bleeding after trauma
Spontaneous joint/ muscle bleeds (Rare)
