Kidney receives approximately 20–25% of the cardiac output. Blood traverses through the kidney primarily to be cleansed. The macro circulation starts with the main renal artery branching into several segments which are short ramifications that divide into the interlobar arteries running up the columns of bertin between neighboring pyramids. In the corticomedullary junction, the interlobar arteries give rise to the arcuate arteries.
From the smaller branches of the cortical ascending arteries emerge the afferent arterioles that feed the glomerular ensemble. Renal venous drainage of the peritubular capillaries commences at all levels in the cortex and medulla and the drainage follows a path flowing counter direction to but anatomically exquisitely similar and closely apposed to the arterial system (arcuate, interlobar veins). This is the basis for the functional arteriovenous shunt. At the renal hilus, the interlobar veins coalesce to form the main renal vein.