人体新陈代谢过程中要不断地排出代谢终产物和过剩的物质。排泄途径为：肺、大肠、皮肤和肾脏。肾脏产生的尿中所含排泄物的种类最多、量也最大，因此它是人体最重要的排泄器官。肾脏能生成尿液，排泄代谢终产物，药物和毒物等；调节体内水盐代谢和酸碱平衡；产生多种生物活性 Metabolism end products and excess substances should be constantly discharged in the process of human metabolism. Pathways of excretion: lung, colon, skin and kidneys. Urine produced by the kidneys contains the largest amount and amount of excrement in urine, so it is the body’s most important excretory organ. Kidney can generate urine, excretion of metabolic end products, drugs and poisons, etc .; regulate the body’s water and salt metabolism and acid-base balance; produce a variety of biological activity