Haemostasis Flashcards
are platelets and anticoagulation factors always present in blood vessels?
yes
when do platelets and anticoagulation factors become activated ?
after damage or abnormal surface
what are the three stages of vessel repair?
clot formation
clot remains confined to site of injury
clot breaks down
what three things are involved in clot formation ?
platelets
vWF
coagulation factors
what does vWF do?
von willebrand factor has receptors on its surface for collagen which is present in the sub endothelium and also to the activated platelets.
therefore this factor binds the collagen and activated platelets together to form a platelet plug
what does vWF stand for?
von willebrand factor
what is the function of the platelet plug?
it holds fibrogen in position
what cleaves the fibrogen into fibrinopeptides ?
thrombin
does fibrinogen have a positive or negative feedback on coagulation?
positive feedback
what substance prevents more clots forming ?
natural anticoagulants
name some natural anticoagulants?
TFPI (tissue factor pathway inhibitor)
anti thrombin
activated protein C and S
what is the reaction which breaks down the clot?
fibrinolysis
name two substances which are apart of the fibrinolytic system ?
t-PA
u-PA
what is the function of the plasminogen activators ?
cleaves the plasmin from the plasminogen which degrades the fibrin clot
what do the activated platelets release for clotting?
alpha and dense granules
what do the dense granules contain?
ADP/ATP
calcium
serotonin
what do the alpha granules contain?
vWF
thrombin
what about the cell membrane is coagulation activation dependant on?
phospholipids
what is the function of scramblase?
responsible for the translocation of phospholipids between the two monolayers of a lipid bilayer of a cell membrane
state some medication which can affect anticoagulation?
aspirin clopidogrel ticagrelor warfarin heparins rivaroxaban
how is heparin administered ?
parentaly (injections)
what does warfarin affect in the body
affects vitamin K and affects coagulation factors
what affect does nitric oxide have on blood vessels?
relaxes vessels hence increases diameter and prevents platelet activation
what affect does prostacyclin have on blood vessels?
relaxes vessels hence increases diameter and prevents platelet activation
