How Do Kidneys Work?

The excretory organ of the human body is the kidney. Two kidneys lie at the back of the abdominal cavity, on either side of the vertebral column and the lower part of the rib-cage, attached to the back wall. They are bean-shaped and red-brown in color. The outer side of the kidney is convex and the inner side is concave, with an indentation called the hilus or hilum. The ureter and renal vein come out from the hilum and the renal artery enters the kidney.

Two ureters arise from each kidney, proceeding downwards to open into the urinary bladder. The funnel-shaped extended part(space) of the ureter is called the renal pelvis. Kidneys are enclosed with a special fibrous membrane, called the renal capsule. Adjacent to the renal capsule is the cortex, and the inner side is the medulla. These regions are composed of connective tissues and blood vessels. Generally, there are 8-12 renal pyramids in the medulla.

The apex of each pyramid is called the papilla. These papilla projects directly into the ureter. Each kidney contains a particular type of tubules called uriniferous tubules. Each uriniferous tubules has two parts, the nephron and the collecting tubule. Urine is produced in the nephron, and the collecting tubules carry urine to the pelvis.