HHP 3500 Lecture Notes - Lecture 31: Endothelium, Thromboxane A2, Coagulation
27 Oct 2016
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Document Summary
Blood composition (5. 5l total): 2. 5 l of blood cells, 3 l of plasma. We need to stop blood loss: how: hemostasis-stoppage of bleeding, most effective in small vessels (hard to stop in high-pressure vessels like arteries) Stimulus of hemostatic response is the exposure of blood to sub endothelial tissues (tissue under endothelial cells) Vessel constriction: when endothelial cells are stimulated, they will release fewer vasodilators, more vasoconstrictors, make vessels constrict, causing increased resistance, therefore limiting blood flow, most relevant in the smallest vessels. Platelet plug can actively contract, with their motor proteins: platelet plug system is limited by mediators (prostacyclin and no) from in-tact endothelial cells, telling it to slow down and inhibiting platelet activation and aggregation. Initiated by either intrinsic pathway (triggered by exposure of plasma proteins to subendothelial tissue) or extrinsic pathway (triggered by binding of plasma protein to a protein located on the membrane of a subendothelial cell)
