7. Bleeding And Thrombosis Flashcards
What do you need to make a blood clot
Plasma and coagulation factor
Platelets and Von wilibrands factor (vWf)
They need to be activated
Natural anticoagulants-confines clot
Fibrinolytic system- removes clot after enough time
Discuss the epithelium
It’s a non stick surface, things don’t want to stick to it,
It produces nitric oxide, heparins, thrombomodulin, prostacyclins
What activates clots?
Abnormal surface- e.g. subendothelial collagen
and physiological activator e.g. tissue factor
Discuss how platelets are involved in clotting?
Platelets contains lots of receptors to things that want to stick to it such a vWF, fibrinogen or things that sense damage e.g. epinephrine. This makes platelets activated and sticky
How do platelets do it’s job?
They contain granules and factors that help the platelet do there job. Alpha and dense granules. The platelets role is to become a clumpy clot and allows for fibrinogen clots
What is the role of platelets?
3 A’s
Adhere
Activate
Aggregation
Provide phospholipid activation for coagulation
What is adhered in platelets?
vFW, fibrinogen
What is activated in platelets
Pathways are activated
Cyclase oxigenase promotes aggregation, aspirin inhibits this
ADP/P2Y12 pathway- clipidogrel inhibits this pathway
How do platelets aggregate?
Form thromboxane, shrink down and clump together.
What is Von wilibrands factor?
A big sticky molecule. Need to have it at sites of vessel damage or else you bleed. Most common bleeding disorder is Von wilibrands disease.
Why do we need vWF
Binding sites for collagen, platelet binding sites, binding sites for factor 8
What consists of a platelet plug?
Platelets
Fibrinogen
vWF- binds platelets to collagen
What do we need to form a permenant clot?
A fibrin clot
How do we form a fibrin clot?
A set of coagulation factors. Like dominoes
They act like dominoes and if they all activate each other then bleeding stops
Why would haemophilia occur?
Coagulation factor deficiency or a factor is excessively inhibited
