The kidneys are paired, bean-shaped organs that are located behind the abdominal peritoneum, along the posterior body wall. Due to the size of the liver, the right kidney is somewhat lower than the left kidney.
Covering the surface of each kidney is a tough, semi-transparent, connective tissue membrane called the renal capsule. This layer also forms a barrier that protects the kidney from infection.
A large renal artery supplies blood to each kidney. These vessels branch from the descending abdominal aorta. The renal artery enters the kidney at the hilum (or hilus), an indented region along the medial border. Also passing through the hilum are the renal vein and ureter. The renal vein transports blood from kidney to the inferior vena cava, and the ureter conducts urine from the tubular system of the kidney to the urinary bladder.
