The kidneys are paired organs 12cmX6cmX3cm in diameter. Each weighs approximately 50 grams. They are located in the posterior part of the abdominal cavity being protected from behind by the lowest four ribs.

The principal function of the kidney is the elimination of waste materials and the regulation of the volume and composition of body fluids. The kidneys possess some endocrine function which include

Red blood cell production

Vitamin D metabolism

Calcium homeostasis.

The functional unit of the kidney is the nephron, each kidney possessing one million units each.