Final answer:
The arcuate arteries lie parallel to the base of the medullary pyramid, branching from the interlobar arteries at the junction of the kidney's cortex and medulla, and supply blood to the nephrons.
Step-by-step explanation:
The arcuate arteries are parallel to the base of the medullary pyramid at the junction of the cortex and the medulla. These arteries are branches of the interlobar arteries that arc over the base of the renal pyramids. The arcuate arteries play a critical role by further branching to form cortical radiate arteries, leading to afferent arterioles that supply blood to the approximately 1.3 million nephrons in each kidney. Nephrons, specifically the juxtamedullary nephrons, are located adjacent to the border of the cortex and medulla, with loops of Henle that extend deep into the renal medulla. The ascending limb of the loop of Henle ascends from the renal medulla to the renal cortex, and the vasa recta, which are branches of the efferent arterioles, run parallel to the loops of Henle.