what are arterioles
An arteriole /ÉrËtÉªÉri.oÊl/ is a small diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries.Arterioles have muscular walls (usually only one to two layers of smooth muscle) and are the primary site of vascular resistance.The greatest change in blood pressure and velocity of blood flow occurs at the transition of arterioles to capillaries.rain arterioles are particularly sensitive to pH with reduced pH promoting vasodilation. A number of hormones influence arteriole tone such as angiotensin II (vasoconstrictive), endothelin (vasoconstrictive), bradykinin (vasodilation), atrial natruretic peptide (vasodilation), and prostacyclin (vasodilation).