Platelets Flashcards
(42 cards)
what is haemostasis?
the stoppage of bleeding
what features of the epithelium prevents adhesion?
nitric oxide and prostaglandins are secreted and collagen covered
what do smooth muscle cells do in the epithelium?
allow contraction and relaxation
what do alpha granules do?
contain adhesive proteins that cause a glue-like effect
what do dense granules do?
contain activators which activate other platelets
what does the vWF receptor bind to?
glycoprotein 1b59
what does collagen bind to?
alpha 2 beta 1 and glycoprotein 6
what does alpha II beta III bind to?
fibrinogen
how does tethering occur?
vWF binds to glycoprotein 1b59 causing a velcro effect
what is activation?
platelet releases granule contents, which opens up adhesion receptor
what binding occurs in activation?
collagen binding to glycoprotein 6
what is adhesion?
single layer of platelets bind to the exposed ECM
what binding occurs in adhesion?
collagen binding to alpha 2 beta 1
what happens in secretion?
platelet releases ADP and TxA2 which bind to their receptors
what is aggregation?
multiple layers of platelets bind to each other
what binding occurs in aggregation?
fibrinogen binds to alpha 2 beta 3
what does tirofiban do?
targets alpha 2 beta 3 so no aggregation
what does aspirin and clopidogrel do?
inhibit activation of platelets so cannot form a clot
what is bernard-souilier syndrome?
abnormality in glycoprotein 1b59 so collagen cannot bind
what is glanzmann disease?
abnormality in the genes for alpha 2 beta 3
what are the symptoms of platelet associated disease?
easy bruising, menstrual bleeding heavy, abdormal bleeding after surgery
what are storage pool deficiencies?
caused by a lack of granules or their content or inability to empty them
what is grey platelet syndrome?
lack of alpha granules and their contents
what is zymogen?
inactive substance that is activated by enzymes
