The renal artery is the blood vessel that carries oxygen-rich blood from the heart to the kidneys. It originates from the abdominal aorta, which is the main artery that carries blood from the heart to the abdomen. The renal vein is the blood vessel that carries oxygen-poor blood from the kidneys to the heart. It drains into the inferior vena cava, which is the major vein that carries blood from the lower body to the heart.