MICROANATOMY

Detailed explanation-1: -Urethra. This tube allows urine to pass outside the body. The brain signals the bladder muscles to tighten, which squeezes urine out of the bladder. At the same time, the brain signals the sphincter muscles to relax to let urine exit the bladder through the urethra.

Detailed explanation-2: -Controlling the outflow of urine are two valves, or sphincters, located in the bladder neck and earliest portion of the urethra. The bladder neck sphincter is under involuntary (autonomic) control while the urethral sphincter has both voluntary and involuntary components.