尿生成和排出的意义： 1.carry out the excretion of metabolic wastes,particularly nitrogenous wastes. 2.maintain the normal water-salt balance of the blood and ,as a consequence the normal blood volume and blood pressure. 3.maintain the acid-base balance of blood.尿生成和排出的意义: 1. carry out the excretion of metabolic wastes, particularly nitrogenous wastes. 2. maintain the normal water-salt balance of the blood and ,as a consequence , the normal blood volume and blood pressure. 3. maintain the acid-base balance of blood