In the cortex, the distal convoluted segment comes in contact with the glomerular blood supply in an adaptation called the macula densa, part of the juxtaglomerular apparatus. The endothelium of the tubule becomes more dense and columnar and is in close apposition to specialized cells of the afferent arteriole. The juxtaglomerlular apparatus is involved in regulating glomerlular filtration rate, systemic blood pressure and thirst via the renin-angiotensin system and the formation of red blood cells via the production of the hormone erythropoietin. Two or more distal convoluted segments empty into a collecting duct, lined with simple cuboidal cells, that descends into a medullary pyramid and empties into a calyx of the renal pelvis. From there urine travels into the renal pelvis to the ureter to the bladder and then out through the urethra.
Blood enters the kidney via the renal artery at the hillus.
The renal artery branches to feed segments of the kidney then branches again to form interlobar arteries. At the interface of the cortex and medulla interlobar arteries become arcurate arteries that further branch to form interlobular arteries. The afferent arteriolar supply to the glomeruli arise from these interlobular arteries. Blood leaves the kidney by following the interlobular veins to the arcuate veins to the interlobular veins that join to form the renal vein which empties into the vena cava. Nervous supply to the kidney is largely from the sympathetic portion of the autonomic system.