Is Vasodilation is a widening of the lumen due to smooth muscle contraction?

No, vasodilation is not a widening of the lumen due to smooth muscle contraction. Vasodilation is the widening of blood vessels, particularly arteries and arterioles, leading to increased blood flow to tissues and organs. It occurs when the smooth muscles in the walls of blood vessels relax, causing the inner diameter (lumen) of the vessels to increase. This relaxation can be triggered by various factors, including chemical signals from nearby tissues, nerve signals from the brain and spinal cord, and the release of hormones such as nitric oxide.