The renal artery, Arterie renalis, leads blood from the aorta to the kidney, and branches off into a number of arterioles when it arrives in the kidney. These arterioles deliver blood to the glomeruli located at the border ofthe renal cortex and medulla. The afferent arteriole (ingoing) leads blood into the capillary network inside the glomerulus. The blood that is not filtered in the glomerulus, and passes out of the capillaries, exits the glomerulus via the efferent arteriole. The efferent arterioles of cortical nephrons will wrap around the proximal and distal tubules, while the efferent arterioles in juxtamedullary nephrons (called thethe vasa recta), wrap around the Loop of Henle. Most fluids and substances transmitted into the nephrons in the glomerulus, is returned into the bloodstream through the vasa recta. The remaining salts, fluid and waste products in the tubule are then excreted as urine.