platelet biochemistry

Question 1

thrombosis

Answer 1

• Formation of clot (thrombus) inside blood vessel
• Platelets have a central role in arterial thrombosis
Heart attack (myocardial infarction)
Stroke
Sudden death

Question 2

platelet shape change

Answer 2

• Activation → shape change
• Smooth discoid →spiculated + pseudopodia
• Increases surface area
• Increases possibility of cell-cell interactions

Question 3

Glycoprotein llb/llla receptor

Answer 3

• On surface of platelet
• 50,000 to 100,000 copies on resting platelet
• Platelet activation
• Increases number of receptors
• Increases affinity of receptor for fibrinogen
• Fibrinogen links receptors, binding platelets together (platelet aggregation)
• Also known as integrin αIIbβ3

Question 4

platelet receptors

Answer 4

• After atherosclerotic plaque rupture
• Platelets adhere to damaged vessel wall
• Collagen receptors bind to subendothelial collagen which is exposed
• GPIIb/IIIa also binds to von Willebrand factor (VWF) which is attached to collagen
• Soluble agonists are also released and activate platelets