| vasodilation | The increase in the internal diameter of a blood vessel that results from relaxation of smooth muscle within the wall of the vessel. This causes an increase in blood flow, but a decrease in systemic vascular resistance. (27 Sep 1997) |
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| active vasodilation | Vasodilation caused by decrease in tonus of smooth muscle in the wall of a vessel. (05 Mar 2000) |
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| passive vasodilation | Vasodilation related to increased pressure in lumen of a vessel. (05 Mar 2000) |