BIO L 460 1st Edition Lecture 22 Outline of Last Lecture I Lymph Vessels II Lymph Nodes III Atherosclerosis IV Blood Clotting a Formation b Anticoagulants Outline of Current Lecture I Blood Clotting a Platelets i Paracrine Factors b Hemostasis c Platelet Release reaction i Von willebrands factor 1 Thromboxane A2 and ADP d Formation of Clot i Coagulation cascade Current Lecture Blood Clotting 1 Platelets thrombocytes don t stick together due to These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Repel because of negative charge b Plasma membrane of endothelial cells has a negative charge c Paracrine factors i Both function to trigger vasodilation and prevent the platelets from sticking together 1 Prostacyclin 2 Nitric Oxide d CD39 enzyme that catalyzes reaction where ADP makes platelets stick AMP and P i e Blood is constantly in motion which prevents blood clot 2 Hemostasis cessation of bleeding a 3 steps i Vasoconstriction smooth muscle of tunica media contract ii Platelet plug petechiae red spots where platelets aren t being properly produced capillaries have been torn open iii Coagulation cascade blood clot 3 Figure 13 7 a Endothelium of intact vessel produces NO vasodilator and prostacyclin a prostaglandin that keeps platelets from sticking together and acts as a vasodilator b CD39 ADP AP P ADP allows platelets to stick so CD39 prevents ADP from building up when clotting is not needed 4 Causes Platelet Release Reaction Possible Essay Question a Damaged Vessel caused by injury b Rupture in endothelium i Platelets come in contact with substances in extracellular matrix 1 collagen 2 Platelets have proteins that stick to collagen c Von Willebrands Factor VWF pitchfork structure protein produced by endothelial cells help platelets adhere to collagen one type of hemophilia caused by a deficiency in this i Degranulation vesicles in platelet look like granules ii Vesicles undergo exocytosis fusing with PM iii Thromboxane A2 prostaglandin and ADP are released 1 TXA2 helps platelets stick so they can clot and form the platelet plug also a vasoconstrictor 2 ADP makes platelets sticky 3 Growth factors released important in stimulation of regeneration of connective tissue 4 Tissue Factor released found in plasma membrane of most cells important in beginning cascade that can lead to platelet blood clot 5 Formation of a Clot a Fibrin network mesh of fibers can contract b Fibrinogen soluble plasma proteins throbrin polymer of fibrin c Prothrombin Thrombin d Serum everything in plasma minus fibrin e Clotting Factors i Mostly plasma proteins in blood f ii Work together to form clot iii Ca2 needed Coagulation Cascade i Intrinsic Pathway 1 Slower 2 Blood only 3 Clots by itself ii Extrinsic Pathway 1 Involves chemicals from tissues 2 Tissue Factors iii Anticoagulants 1 Aspirin inhibits COX 1 inhibits platelet release reaction
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