What's the advantage of holding urine in your body?

There are many disadvantages of frequent urination: some people often urinate frequently, such as long meeting time, traveling abroad, taking long-distance buses, outdoor toilets, fear of cold in winter and other factors, which make urine stay in the bladder for a long time, resulting in excessive bladder pressure. The pressure of normal bladder wall is limited. Under normal pressure, the inner bladder membrane has a self-protection mechanism, which can engulf bacteria and prevent invasion. When there is too much urine in the bladder, which exceeds the pressure that the normal bladder wall can bear, it will damage the inner bladder membrane, and this ability of self-protection will also be damaged, and bacteria will take advantage of it and cause cystitis. The cilia of some pathogenic bacteria can attach to the urinary tract mucosa and go up to the renal pelvis through the ureter, causing pyelonephritis. Clinically, it will be manifested as low back pain, frequent urination, dysuria, hematuria and other symptoms. Long-term repeated chronic infection can also cause renal function damage, and even uremia!