S1W15 Coagulation and platelet aggregation (FS)

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What are the functions of platelets?
Maintenance of vascular integrity
Initial arrest of bleeding by platelet plug formation
Stabilisation of haemostatic plug by contributing to fibrin formation
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What does platelet adhesion require?
Synergistic function of different platelet receptors
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What are some extracellular matrix components that react with platelets?
Collagen
vWF
Fibronectin
other adhesive proteins
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What does platelet adhesion occur?
Following blood vessel injury, platelets adhere to the exposed subendothelial connective tissues
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What is the role of vWF?
Initiates platelet adhesion and sustains platelet aggregation - this occurs through binding of GPIba
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What happens to platelets after adhesion?
They become more spherical and extrude long pseudopods which enhance interaction between adjacent platelets
Generate biologically active mediators
Degranulation
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What is binding of platelets and other cell types mediated by?
P-selectin (a.k.a CD62p)
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What does the release of ADP and thromboxane A2 do?
Cause additional platelets to aggregate at the site of vascular injury
ADP causes platelets to swell and encourages the platelet membranes of adjacent platelets to adhere to each other
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What are some markers of plt activation?
PF4
PDGF
Thromboglobulin(b-TG)
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What are some aggregating agents (agonists)?
Collagen
ADP
Epinepherine
Arachidonic acid
The antibiotic ristocetin
Thrombin
Serotonin
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What are the two paths of the clotting pathway?
Intrinsic and extrinsic, originate separately but converge at a specific poit, leading to fibrin activation
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What is the extrinsic pathway?
Damaged endothelial cells release tissue factor (TF) which goes on to activate factor VII to VIIa
Factor VIIa goes on to activate factor X to factor Xa then the common pathway (prothrombin into thrombin)
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What is the intrinsic pathway?
It begins with the activation of factor XII which becomes factor XIIa after exposure to collagen then a pathway of factors eventually keads to factor Xa
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What is fibrinolysis?
The breakdown of a clot
Repair and healing mechanism
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What are the main key players in fibrinolysis?
Plasminogen
Tissue plasi=minogen activator (t-PA) and urokinase (u-PA)
a2-antiplasmin
Also protein C and S
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Card 2

Front

What does platelet adhesion require?

Back

Synergistic function of different platelet receptors

Card 3

Front

What are some extracellular matrix components that react with platelets?

Back

Preview of the front of card 3

Card 4

Front

What does platelet adhesion occur?

Back

Preview of the front of card 4

Card 5

Front

What is the role of vWF?

Back

Preview of the front of card 5
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