Whooshing downwards, the fluid enters the urethra and stops short at the external urethral sphincter.

液体飞速的向下流进尿道，从膀胱经尿道排出体外。

The brain can counter it if it's not a good time to urinate by sending another signal to contract the external urethral sphincter.

通过发射另一个信号来控制尿道外括约肌大脑会判断现在是不是排尿的合适时机。

The external urethral sphincter is one of the muscles of the pelvic floor, and it provides support to the urethra and bladder neck.

尿道外括约肌是一种盆底肌，它向尿道和膀胱颈提供支撑。

But under normal circumstances, your decision to urinate stops the brain's signal to the external urethral sphincter, causing it to relax and the bladder to empty.

但是在正常情况下，你要排尿的决定阻止了大脑向尿道外括约肌发出信号使得它开始放松，膀胱排空。