Overview Introduction Anatomy the kidneys are retroperitoneal structures that filter blood and produce urine excrete excess salts, fluid, and waste products (e.g., uric acid, urea, and creatine) from the body resorb nutrients back into the blood secrete erythropoietin and renin hydroxylate 25-hydroxy-vitamin D into 1,25 dihydroxy-vitamin D the suprarenal glands (adrenal gland) are above the kidneys a component of the endocrine system blood flow renal artery → segmental artery → interlobar artery → arcuate artery → cortical radiate artery → afferent arteriole → glomerulus → efferent arteriole → vasa recta → peritubular capillaries → venous outlfow the left kidney is typically used for renal transplantation due to left renal vein's longer length