The glomerulus receives its blood supply from an afferent arteriole of the renal arterial circulation. This blood leaves the glomerulus via the efferent arteriole, which supplies the peritubular capillaries. Each glomerulus receives its blood supply from an afferent arteriole of the renal circulation. The walls of the afferent arteriole contain specialized smooth muscle cells that synthesize renin. It is found between afferent arteriole and the distal convoluted tubule of the same nephron. The rest passes into an efferent arteriole. The JGA is located between the thick ascending limb and the afferent arteriole. Hand-warming involves arteriole vasodilation produced by a beta-2 adrenergic hormonal mechanism. Hand-cooling involves arteriole vasoconstriction produced by the increased firing of sympathetic C-fibers. Histologically, glomus tumors are made up of an afferent arteriole, anastomotic vessel, and collecting venule. A "metarteriole" is an arteriole which bypasses capillary circulation. Spider angiomas form due to failure of the sphincteric muscle surrounding a cutaneous arteriole. Each fibre is accompanied by an arteriole and one or more nerve fibres. Arteriolosclerosis is the term specifically used for the hardening of arteriole walls. This makes the venule form an hourglass shape around the arteriole.