BIOC63H3 Chapter Notes -Thromboxane A2, Endothelium, Blood Vessel
Document Summary
When blood vessels are damaged or ruptured, the hemostatic response must be quick, localized to the region of damage, and carefully controlled. Three basic mechanisms reduce blood loss: 1) vascular spasm, 2) platelet plug formation and 3) blood clotting (coagulation). These mechanisms are useful for preventing hemorrhage (loss of blood) in smaller blood vessels, but extensive hemorrhage in larger vessels usually requires medical/veterinary intervention. __ when arteries or arterioles are damaged, the circularly arranged smooth muscle in their walls contracts immediately. It reduces blood loss for several hours, during which time the other hemostatic mechanisms go into operation. The spasm is probably caused by damage to the smooth muscle and from reflexes initiated by pain receptors. Two types of granules are present in the cytoplasm: These contain clotting factors and platelet-derived growth factor (pdgf) which can cause proliferation of vascular endothelial cells, vascular smooth muscle fibers, and fibroblasts to help repair damaged blood vessel walls.
