The circuit that connects the heart and lungs?

Blood vessels. Arteries and arterioles direct oxygenated blood to the kidneys as well as your other major organs and musculature. Then veins and venuoles push deoxygenated blood back to your heart. Oxygenated Blood leaves your Left ventricle of your heart and enters the aorta which branches into three segments, I believe it is the subcostal descending aorta which feeds the kidnesys.