(Posted:02-Jul-2015)

General organization of the kidney and urinary tract: The two kidneys lies on the posterior wall of the abdomen,outside the peritoneal cavity.The medial side of each kidney contains an indented region called the hilum through which pass the renal artery and vein,lymphatics,nerve suppy,and ureter which carries the final urin from the kidney to the bladder,where it is stored until emptied.The kidney is surrounded by a tough,fibous capsule that protects its delicate inner syructures. If the kidney is bisected from top to bottom,the two major regions that can be visualized are the outer cortex and the inner medulla regions. The medulla is divided into 8 to 10 cone shaped masses of tissue called renal pyramids. The base of each pyramid originates at the border between the cortex and medulla and terminates in the papilla,which project into the space of the renal pelvis,a funnel shaped continuation of the upper end of the ureter.The outer border of the pelvis isdivided into open ended pouches called major calyces that extend downward and divided into minor ccalyces,which collect urine from the tubules of each papilla. Renal blood supply: The renal artery enters the kidney through the hilum and then branches progressively to form the interlobar arteries,arcuet arteries and afferent arterioleswhich lead to glomerular capillaries,where large amount of fluid and solutes are filters to begin urine formation. The renal circulation is unique in having two capillary beds,the glomerular and peritubular capillaries,which are arranged in series and separated by the efferent arteriols,which help regulate the hydrostatic pressure in both sets of capillaries.The peritubular capillaries empty into the vessels of the venous system,which run paralllel to the arteriolar vessels. The blood vessels of the venous system progressively form interlobar vein,arcuate vein,interlobar vein and renal vein which leaves the kidney besides the renal artery and ureter.