MICROANATOMY

Detailed explanation-1: -Passing your urine happens when the brain tells the bladder muscle to tighten. This squeezes urine from the bladder. The brain then tells the sphincter muscles surrounding the urethra to relax. This lets the flow of urine go through the urethra and out of the body.

Detailed explanation-2: -A PVR volume of less than 50 mL is considered adequate bladder emptying; in the elderly, between 50 and 100 mL is considered normal. In general, a PVR volume greater than 200 mL is considered abnormal and could be due to incomplete bladder emptying or bladder outlet obstruction.