phys-blood clot notes

phys-blood clot notes - Blood Clotting What happens when...

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Blood Clotting What happens when you cut yourself? - bleed How do you stop bleeding? -hemostasis = bleeding stops hemo=blood stasis= not moving What does blood do? -Distribute: 1. water 2. food 3. oxygen -Form a solid plug to stop bleeding when blood vessels are damaged (hemostasis) Blood Clotting- hemostasis -there are 3 separate, but overlapping hemostatic mechanisms 1. formation of platlet plug (thrombus) 2. production of a web of fibrin - proteins that penetrate and surround the platelet plug to strengthen it 3. vasocontriction -shut down blood supply at area of wound (because blood flowing through would disrupt platelet plug) Platelet Plug: -platelets= thrombocytes -no nucleus -made by pinching off pieces of specialized bone marrow cells ( megakaryocytes ) -short life span (destroyed by liver or spleen ) -if too few= excessive bleeding -if too many= blood clot Function of Platelets: -aggregate -stop bleeding when a blood vessel is damaged * they do not bind to intact endothelium because of the inhibitors How does the platelet know of the vessel is damaged? -blood vessels are lined with endothelium -endothelium released two inhibitors: 1. NO (nitric oxide) 2. PGI2 (protacylin) * these inhibitors stop the platelets from aggregating STEP ONE: FORMATION OF PLATELET PLUG: -endothelium covers the sub-endothelium (until wound)
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This note was uploaded on 04/07/2011 for the course PHYS 100 taught by Professor Balassare during the Fall '10 term at Saint Louis.

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phys-blood clot notes - Blood Clotting What happens when...

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