Unformatted text preview: Hemostasis Hemostasis is the homeostatic mechanism that prevents the loss of blood due to trauma or other damage to blood vessels. It is effective in small vessels, although larger vessels may require medical intervention to prevent serious damage or death. The three stages of homeostasis are vascular spasm , platelet plug formation and coagulation . (See Figure 5). Figure 5 Vascular Spasm Vascular spasms promote the prompt constriction of a broken blood vessel. Several stimuli cause this constriction. Pain receptors not only signal to the brain that damage has occurred, but also to the smooth muscle layer of the damaged vessel to cause constriction. This type of stimulation may only last a few minutes; more long-lasting constriction is chemically stimulated. Platelets respond to endothelin released by damaged endothelial cells and release serotonin , which is a potent vasoconstrictor. The vascular spasm stage of hemostasis allows time for the other two mechanisms to work....
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- Fall '10
- Anatomy, Platelets, Platelet, vascular spasm, platelet plug formation