 The myogenic effect refers to the inherent attempt of vascular smooth muscle surrounding arterioles and arteries to maintain the tension in the wall of these blood vessels by dilating when internal pressure is reduced and to constrict when wall tension increases.Functional hyperaemia, metabolic hyperaemia, arterial hyperaemia or active hyperaemia, is the increased blood flow that occurs when tissue is active.It is widely thought that active hyperaemia is mediated by the increased synthesis and/or release of vasodilatory agents during periods of heightened cellular metabolism.