Urinary System

Every day the kidneys filter 140 litres of fluid, removing excess water, salts and waste products, and returning all but 0.5 to 1 litre of it back into circulation. Besides filtering waste, the kidneys also help to regulate blood pressure and reclaim essential substances, such as minerals. The waste fluid, urine, is excreted on average three to four times daily. In men, the urethra is five times longer than in women. As a result, men experience problems with urinary control and infection less frequently than women. Kidney stones, in contrast, are several times more common in men.

In complementary medicine, the kidneys are seen as the key to the elimination of toxins. The strength of the kidneys is thought to indicate an individual's constitutional ability to resist disease. many traditional remedies act by increasing the rate of urine production. In traditional Chinese medicine, the kidney is said to store jing, the essence of life.