Kidneys
Here we show the single kidney opened/bissected along its long axis into two halves (we cut from the lateral margin -- the ureter is still intact and connected to the renal pelvis).
The kidney is made up of three different regions internally: the outer cortex, the middle medulla (with the renal pyramids) and the inner-most renal pelvis.
Scroll down the page for more details of these specialized regions.
As blood enters the kidney via the renal artery, it is forced through a maze of small tubules (nephrons)—the functional unit of the kidney. These nephrons have their proximal end within the renal cortex.
The nephrons filter water, ions, nitrogenous wastes, and other materials from the blood and form urine that is then passed through the collecting ducts to the base of the renal pyramids and into the renal pelvis.
The urine collects in the renal pelvis, which drains into the ureter (indicated with the label). Urine travels in the ureter for storage in the urinary bladder.
Filtered blood exits the kidney via the renal vein.