What happens during a vascular spasm and what triggers it?
Vasoconstriction of bv
Tissue damage
Chemicals released by endothelial cells
Pain reflexes
3 steps to hemostasis?
1- vascular spasm
2- plug formation
3- coagulation
How does a platelet plug form?
Exposed collagen fibers become sticky, platelets attach and release chemicals causing more to attach and plug forms
How does coagulation happen?
Blood transforms into gel
And reinforces plug with fibrin strands
What is a procoagulant?
Inactive plasma clotting protein
What is an anticoagulant?
Prevents clotting
Three phases of coagulation?
Prothrombin activator formed
& converted into thrombin
Thrombin catalyzes fibrinogen to for fibrin mesh
What are the two pathways to prothrombin activator?
1) intrinsic pathway
2) extrinsic pathway
What’s an intrinsic pw triggered by?
Negatively charged surfaces, and it uses factors within blood
What is an extrinsic pw?
Triggered by exposure to tissue factor or 111, faster than intrinsic
How is prothrombin activator formed?
Initiated by a pw Triggered by tissue damage Involves procoagulant a Each pw cascades towards factor x - complexes with ca,pf3 and V to form pt activator
How does prothrombin become thrombin?
Prothrombin activator
What is the pw to the fibrin mesh?
Thrombin changes fibrinogen-> fibrin
And those strands become basis of clot, becomes gel trap, thrombin activated xlll which cross links fibrin
How does clot contraction and tissues get repaired?
Actin myosin contract
The platelets then pull on fibrin which squeezes serum of clot and edges pulled together
Pgdf stimulated bv walk building
Vegf stims growth of endothelium lining bv
Fibrinolysis?
Plasminogen is converted into plasminogen by tpa, xll, thrombin
Plasminogen is fibrin digesting enzyme
What limits clot formation/growth
Swift removal and dilution, and inhibition of clotting factors
What inhibits thrombin?
Heparin
What is a thrombus?
Clot in unbroken bv
Embolus?
Floating thrombus
Warfarin?
Inhibits clotting
Aspirin
Prevents platelets from sticking together
What are packed red blood cells used for?
Restore o2 caring capacity
What are different blood types due too?
Antigens on rbc
What do glycoproteins antigens do?
Promote agglutination and agglutinogens
What is agglutinogens
No clotting factors and no fibrin mesh is formed
SA of rbc stick together because of interactions between glycoproteins and plasma agglutinins