There are three basic functions of the kidney

(A) generating urine excreted metabolites. Body's metabolic processes produce a variety of waste, most of the blood of waste by glomerular filtration, tubular secretion, and excreted in the urine.
(2) to maintain fluid balance and acid-base balance. Kidneys by glomerular filtration, tubular reabsorption and secretion, discharge excess water in the body, regulating acid-base balance, maintain a stable internal environment.
(3) endocrine function.
① renin secretion, prostaglandins, bradykinin. Prostaglandins to regulate blood system - through the renin - angiotensin - aldosterone system and bradykinin - bradykinin.
② erythropoietin. Stimulate the bone marrow.
③ activity VitD3. Regulate calcium and phosphorus metabolism.

④ hormone degradation of many places - such as insulin, gastrointestinal hormones. When these hormones renal insufficiency T1 / 2 was significantly prolonged, causing metabolic disorders.
⑤ renal hormone target organs. Such as parathyroid hormone, calcitonin. And regulation can affect kidney function.
Visible, kidney plays an important function in maintaining stability in the internal environment.