Blood Coagulation and Wound Healing Flashcards
what is the process of blood clotting/ coagulation? (6)
injury/rupture to blood vessel
blood vessel around wound constricts (reduces blood flow to the damaged area)
activated platelets stick to the injury site
platelets become sticky and clump together to form a platelet plug
platelets and damaged tissue release clotting factors
blood clotting mechanism to form fibrin which acts like a mesh to stop the bleeding
primary hemostasis
vasoconstriction and platelet response
what mediates platelet aggregation at the site of injury in primary hemostasis (4)
platelet receptors
platelet-derived agonists
platelet-derived adhesive proteins
plasma-derived adhesive proteins
secondary hemostasis
clotting cascade
what does secondary hemostasis consist of?
the cascade of coagulation serine proteases that culminates in cleavage of soluble fibrinogen by thrombin
Thrombin cleavage generates insoluble fibrin that forms a cross-linked fibrin mesh at
the site of an injury
fibrin generation occurs simultaneously to
platelet aggregation
what do clotting factors do
convert prothrombin to thrombin
what does thrombin do
convert fibrinogen to fibrin (insoluble)
damaged blood vessel
injury to vessel lining triggers the release if clotting factors
formation of platelet plug
vasoconstriction limits blood flow and platelets form a stick plug
development of clot
fibrin strands adhere to the plug to form an insoluble clot
platelets release important signaling molecules upon initial binding to
collagen
Platelets that stick to collagen undergo a release reaction, in which they secrete (3)
ADP, serotonin, and thromboxane A2
Serotonin and thromboxane A2 cause
vasoconstriction
platelet plug process
ADP and thromboxane A2 attract other platelets and make them stick to the growing mass of platelets that are stuck to the collagen in the broken vessel
what can platelets secrete?
serotonin
what does serotonin cause?
blood vessels to spasm, decreasing blood flow to that area
the initial binding of platelets to vWF is mediated by
glycoproteins that are necessary for platelet tethering (ex. loosely bound), but do not promote strong adhesion (ex. GPlb amd la are not enough, even in conditions of high shear)
firm adhesion of platelets to the sub endothelial is mediated by a glycoprotein called
GP2B/3A
the GP2B/3A integrins on resting platelets bind
poorly to its ligands