General

The kidneys

Oxygen-rich blood also flows to the kidneys. The body has two kidneys. They can be seen as the body’s purification plants.

All the blood in the body (5 to 6 litres) passes through the kidneys every five minutes. About one eighth of it is filtered there each time to remove waste products or drugs from the body.

The oxygen-rich blood flows into increasingly smaller blood vessels in the renal cortex, the outer part of the kidney. The cortex of each kidney contains about one million tiny units known as nephrons, which filter the blood.