PSL301H1 Lecture Notes - Lecture 5: Von Willebrand Factor, Vasospasm, Tissue Factor

• School: UTSG
• Department: Physiology
• Course: PSL301H1
• Professor: French, Gramolini, Richardson, Wong

Document Summary

Recall: hematopoiesis the formation of platelets come from pre-cursors called megakaryocytes. How is blood clotting regulated: platelets are needed for blood clotting. The edges of the megakaryocytes break off to form platelets: half-life of platelets is 10 days, thrombopoietin stimulates the production of platelets i. e. low platelet level means the increased secretion of thrombopoeitin. With an injury to the blood vessel occurring: the vascular phase narrows the vessel (vascular spasm) this occurs under neurogenic (neurons present) and myogenic (muscular) control. Vasoconstriction is prolonged by factors released from different places in the damaged vessel (platelets or endothelial cells that line the capillary: serotonin, endothelin-1, thromoboxane a2 enhances vasoconstriction, platelet phase. During platelet activation platelet changes its shape form from a dislike fragment to a spikeier outer surface- which helps aggregation. Fibrin is used to help reinforce loose platelet plugs which is cross-linked via factor xiii.