. Discuss Regulation of Kidney Function
Although it is true that the kidneys can excrete hypertonic urine, it is not always beneficial for them to do so. Nevertheless, if we are dehydrated and water is unavailable, the kidneys can excrete a small volume of hypertonic urine as concentrated as 1200 mosm/L, making it possible to discharge wastes with a minimal water loss. But if we have consumed an excessive amount of fluid, the kidneys can actually excrete a large volume of hypotonic urine as dilute as 70 mosm/L, making it possible to eliminate a lot of water without losing essential salts. The kidney is a versatile osmoregulatory organ, where water and salt reabsorption are subject to a combination of nervous and hormonal controls.