The kidneys are paired, continuously functioning organs. Constantly forming urine, they excrete metabolic waste, regulate the water and salt metabolism between the blood and other tissues, participate in the regulation of BP and acid-base balance in blood, have endocrine functions.
All kidney structures are related to one another, so a lesion of a single structure almost always causes secondary damage to other ones. However, some specific structures are affected more in certain diseases. Depending on that, renal diseases may be divided into 4 groups: predominant lesions of glomeruli, tubules, stroma (interstitium), or blood vessels. Etiological factors affect renal structures in different ways. Thus, immune diseases most often cause glomerular lesions, while tubular and interstitial structures are predominantly affected in toxic or infectious exposure. However, the compensatory reserves of kidneys are great. It means that before their functional failure develops, significant compensatory and adaptive changes usually occur in kidneys.