 It is thought that vasodilators (released from active muscle fibers) can stimulate a local capillary endothelial cells which, in turn, causes the conduction of a vasodilatory signal to upstream arterioles, this then elicits arteriolar vasodilation consequently, creating a pathway of least resistance so blood flow can be precisely direct to capillaries supplying the metabolically active tissue.Conversely, when a tissue is less metabolically active, it produces fewer metabolites which are simply washed away in blood flow.Since most of the common nutrients in the body are converted to carbon dioxide when they are metabolized, smooth muscle around blood vessels relax in response to increased concentrations of carbon dioxide within the blood and surrounding interstitial fluid.