The human kidney is located below the diaphragm, on both sides of the spine, on the posterior abdominal wall of the lateral posterior lumbar region, shaped like a fava bean, one on each side; the right kidney is slightly lower than the left kidney because of the presence of the liver on it. If compared with the ordinary abdominal x-ray, it is approximately at the midpoint of the twelfth thoracic vertebra to the midpoint of the third lumbar vertebra. Each kidney weighs about 120-150 grams, is 10-12 cm long, 5-6 cm wide, and 3 cm thick. Female kidneys are usually smaller. The kidney is divided into two parts: the lateral layer of cortex and the medulla of the medial layer. The tip of the medulla forms a papilla shape connected to the calyces. The urine formed in the kidney reaches the bladder from the papillary part through the calyces, renal pelvis, and ureter, passes through the urethra, and is excreted from the body. The basic working unit of the kidney is called the “nephron unit” (Figure 2), and each kidney consists of about one million nephron units. The renal unit consists of a renal tubule and an attached tubule. The renal tubules are located in the cortical part of the kidney. Each renal tubule consists of a glomerulus and a capsule that surrounds it. The core of the glomerulus is a network of capillaries that is connected at both ends to the small input and output arteries, respectively. The glomerulus is surrounded by a capsule. The epithelium of the dirty layer of the capsule and the epithelium of the wall layer of the capsule continue with the epithelium of the renal tubules. The lumen of the renal capsule communicates with the lumen of the renal tubules. The renal tubules are divided into proximal tubules, medullary loops and distal tubules, and the distal tubules finally converge into the collecting duct. The function of the renal unit is mainly to produce urine, including the filtration of the glomerulus and the reabsorption and secretion of the renal tubules. Although the collecting ducts are different from the renal unit in terms of occurrence and structure, they are closely related to the renal tubules in terms of function and play an important role in the process of urine production, especially for urine concentration. The glomerulus and the tubule, each with a different physiological role. The glomerulus is responsible for filtration and is located within the cortical layer; the tubules are responsible for reabsorption and secretion. Waste products from the body are transported through the bloodstream to the kidneys, where they are filtered and excreted into the urine. In fact, the kidneys are responsible for excreting nitrogenous wastes produced by the body’s daily protein metabolism, in addition to their regulatory, synthetic and metabolic roles. Water, sodium, potassium and other electrolytes in the body must be regulated by the kidneys in excess or deficiency to maintain the normal quantity and quality of body solutions (body fluids), and also have the role of maintaining a certain pH (acidity) of the blood. The kidney is an important organ for the synthesis and secretion of hormones in the body, which is related to the production, activity and breakdown of hormones and vitamins required for the regulation of blood pressure, bone metabolism, glucose metabolism, hematopoietic system, especially erythropoietin (EPO) and active vitamin D3 production; it is also involved in the metabolism of other hormones, such as insulin, gastrin (gastrin), parathyroid hormone, etc. ), parathyroid hormone, etc., thus participating in the regulation of endocrine function. Since the blood flow of the kidney accounts for about 1/5 to 1/4 of the blood output of the heart, the complexity and importance of the physiological functions of the kidney are closely related to its abundant blood flow.