KIDNEY
Human excretory system consist of a pair of kidney, one pair of ureters, a urinary bladder and urethra. Kidney are reddish brown, been shaped structure situated between the level of last thoracic and third lumber vertebra close to the dorsal inner wall of the abdominal cavity. Each kidney of an adult human measures 10-12 cm in length, 5-7cm in width, 2-3cm in thickness with an average weight of 120-170gm . Toward the inner concave surface of kidney is a notch called hilum through which ureter, blood vessels and nerve enter. Inner to the hilum is a broad funnel shaped space called the renal pelvic with projection called calyces. Outer layer of kidney is a tough capsule, inside the kidney, there are two zones- an outer cortex and an inner medulla. The medulla is devided into a few conical masses projecting into the calyces . The cortex extends in between the medullary pyramids as renal columns called Column of Bertini. Each kidney has nearly one million complex tubular struct...
