Describe the structure of kidneys.

Explanation

`star` Kidney is bean shaped structure, the outer surface of kidney is convex and inner surface is concave where it has a deep notch called hilum.
`star` A longitudinal sections of the human kidney shows two distinct regions namely the outer cortex and the inner medulla.
`star` Medulla is divided into multiple cone shaped masses of tissue called renal pyramids.
`star` The renal pyramids are separated by the projections of the cortex called columns of Bertin.
`star` The tips of the pyramids are renal papilla.
`star` Renal papilla projects into cup like calyces, formed by the funnel shaped pelvis, which continues out as the ureter. Ureter carries urine into urinary bladder.
`star` In cortex and medulla, nearly one million nephrons are present. They are structural and functional units of kidney. They are embedded in the loose connective tissue of cortex and medulla.
`star` In addition, kidney contains a network of blood capillaries, lymph sinuses and intestitial fluid in intra cellular spaces.
`star` The kidney gets blood supply through renal artery and blood from kidney is carried out by renal vein.