The Physiological Significance of Urea

Abstract

Inasmuch as they are the end products of katabolism, the carbon dioxide and urea in the blood have been regarded merely as waste products on their way to the excretory organs until the former was shown to play a very important role as the regulating stimulus to the respiratory apparatus. Urea, on the other hand, has not up to the present time been shown to subserve any useful function in the animal body. Nevertheless it is well known that the kidney maintains the concentration of urea in the blood at a remarkably constant level and that only very slight variations of this level are found in health.