Vertebrates have adapted to large variations in environmental conditions in each of which the internal environment of volume and solute composition must be maintained within narrow limits. In mammals, some 8090% of the total osmolality is made up of sodium and chloride ions. To maintain their highly regulated internal environments, animals must be in balance a state termed homeostasis that is achieved through complex positive and negative feedback mechanisms.
Keywords: urinary excretion in vertebrates; fluid balance in vertebrates; osmotic regulation; nephron; kidney




