We just learned about the Renal Cortex.
Another part of the kidneys is the Interlobular Arteries and Veins.
These are the arteries that bring fresh oxygenated blood to the kidneys and the veins that take the used up deoxygenated blood away from the kidneys.
They are inside the Renal Capsule, and go around the kidneys to make sure there is a fresh supply of clean blood for the kidneys being pumped in every heartbeat.
(from: wikipedia - interlobular arteries)
Kid Facts - Blast from the past: Auricle