Introduction to Coagulation and Platelet Aggregation Flashcards
What are platelets?
These are cytoplasmic fragments.
What is the function of platelets in haemostasis ?
Maintenance of vascular integrity.
Initial arrest of bleeding by platelet plug formation.
Stabilisation of homeostatic plug.
Which process can’t platelets undergo?
Can’t undergo mitosis.
What can platelets do?
These platelets have proteins which allow them to stick to the gaps in the blood vessel wall and thus, stick to each other.
What is platelet adhesion?
This is when single platelets BIND via specific membrane receptors to cellular and extracellular matrix constituents of the vessel wall and the tissues.
Why is platelet adhesion important?
This is an early phase of platelet activation and LIMITS bleeding by promoting platelet aggregation and clot formation.
What is another name for clot formation?
This is known as Thrombosis.
What is platelet adhesion used to treat?
Used to treat vascular injury.
What is the purpose of fibronectin?
Involved in cell adhesion // growth // migration // differentiation
What is the function of a von Willebrand factor?
1) Acts as a bridging molecule at the sites of vascular injury for normal platelet adhesion.
2) Promotes platelet aggregation.
What are the 2 main binding sites for platelets to go attach on to the vWF?
GPIb - IX - V complex Integrin aIIb(beta)3
How are platelets activated?
They are activated by a number of agonists like ADP and collagen.
Why is collagen important for platelet activation?
Important for potentiation of platelet activation.
What is GP VI?
This is a glycoprotein receptor for collagen which is expressed in platelets.
It is a receptor for thrombus formation on banded collagen fibres.
Why is degranulation IMPORTANT?
Important marker of platelet activation = characterised by DISAPPEARANCE of platelets secretory granules from the platelet interior.
What is the purpose of thrombin and ADP being released?
Releases secondary agonists = THROMBOXANE.
What is p - selectin?
Triggers intracellular signalling = Involved in platelet activation and aggregation.
What is a thrombus?
This is a formation of BLOOD CLOTS in the blood vessels.
What is platelet release reaction?
Cells have to be activated by SPECIFIC LIGANDS. These interact with platelet membrane receptors via G - protein coupled receptors.
What is collagen and thrombin?
Potent activators of platelets.
These platelets are activated via thrombin // collagen.
Where is thrombin activated?
Vascular Injury and vessel wall collagen.
How is ADP actively and passively secreted?
It is ACTIVELY secreted from platelets dense granules and PASSIVELY secreted via damaged erythrocytes and endothelial cells.
In terms of platelet activation what are the markers?
PF4
PDGF
Thrombaglobulin
What do the platelet markers have in common?
These are all clothing factors.
