Human kidney is the “sewer” of human body. As we all know, once the city’s sewerage system is destroyed, there will be a bad situation of sewage flowing and bad smell. The same is true for the human body. Kidney destruction, the same is “sewage flow”, that is, the body of various metabolic wastes, toxins, flow throughout the body, and poisonous body tissues, organs and cells, and even endanger the life of cells. As the basic unit of the human body – cells are destroyed, then, human life and normal physiological activities of course, also affected, for the human body environment, not a bad smell, but difficult to survive. Due to a variety of etiological factors, the excretory function of the kidneys decreased significantly, toxic substances are retained, the body’s water, electrolytes, acid-base balance disorders, which led to a variety of symptoms, such as poor taste, nausea, vomiting, urinary edema, chest tightness, itchy skin, fatigue, mental disorders and even coma, clinically referred to as uremia, that is, renal failure. So, what are the roles of the kidneys? 1, maintain water balance: the kidneys are through the production of urine to achieve this function. Generation of urine is the main function of the kidneys, urine production from plasma, through the glomerular filtration, tubular reabsorption, tubular secretion of the three processes to complete. In these three processes, in addition to the generation of urine, the kidneys at the same time according to the amount of water in the body to regulate the amount of urine, so as to maintain the water balance, to maintain the normal life of people. 2, the excretion of metabolic products and harmful substances (poisons, drugs, etc.): the kidneys through the generation of urine on the plasma filtration of the body’s metabolic products and some other poisons into the human body, chemical drugs filtered out, retaining water and nutrients, and by means of the excretion of urine will be these wastes and harmful substances outside of the body, so as to ensure that the stability of the environment within the human body. 3.Maintaining acid-base balance: Kidneys regulate the acid-base balance in the body by discharging acidic substances and reabsorbing alkaline substances, and also maintain the acid-base balance by controlling the ratio of discharged acidic and alkaline substances. 4, to maintain the composition of body fluids, to maintain the electrolyte balance of body fluids: the kidneys can regulate the useful substances of the human body, such as plasma albumin, glucose, amino acids, hormones, vitamins and inorganic salts, such as potassium, sodium, chlorine, etc., so that they are present in the body according to a certain proportion and concentration, in order to play a role in maintaining the normal life activities of the human body. 5, endocrine function: the kidney can secrete and synthesize some substances, play a role in regulating the physiological functions of the body. It secretes renin and prostaglandins, which play a role in regulating blood pressure and water and salt metabolism by affecting the generation of angiotensin II. It participates in hematopoiesis through the production of erythropoietin, which stimulates the proliferation and differentiation of the red lineage of the bone marrow and promotes erythropoiesis. It synthesizes 1,25-dihydroxyvitamin D, which participates in the regulation of calcium and phosphorus metabolism and plays a role in maintaining the normal structure and function of bones. From the above understanding of the function of the kidneys, we can see that the kidneys are not just a simple excretory organ, but an important organ that has a key influence on the internal environment and normal physiological activities of the human body, which is of great significance in maintaining human life.