BIOL-242 Lecture Notes - Lecture 9: Megakaryoblast, Thrombopoietin, Prostacyclin
28 Apr 2020
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Document Summary
Granules contain serotonin, ca 2+ , enzymes, adp, and platelet-derived growth factor (pdgf) Normal = 150,000 - 400,000 platelets/ml of blood. Form temporary platelet plug that helps seal breaks in blood vessels. Circulating platelets kept inactive and mobile by nitric oxide (no) and prostacyclin from endothelial cells lining blood vessels. Age quickly; degenerate in about 10 days. Fast series of reaction for stoppage of bleeding. Requires clotting factors, and substances released by platelets and injured tissues. Most effective in smaller blood vessels: platelet plug formation. Platelets stick to collagen fibers via plasma protein von willebrand factor. Swell, become spiked and sticky, and release chemical messengers. Adp causes more platelets to stick and release their contents. Serotonin and thromboxane a 2 enhance vascular spasm and. Vitamin k needed to synthesize 4 of them. Prothrombin activator formed in both intrinsic and extrinsic pathways. Coagulation phase 1: two pathways to prothrombin activator. Initiated by either intrinsic or extrinsic pathway (usually both)
