The internal urethral sphincter automatically and involuntarily opens, and the urine is released.

尿道内括约肌自然而然的张开，尿就排出来了。

Simultaneously, the internal urethral sphincter opens. This is called the micturition reflex.

同时，括约肌内壁开始打开。这叫做排尿反射。

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。

Simultaneously, the internal urethral sphincter opens.

同时，尿道内括约肌打开。

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。

The urethral sphincter is a collective name for the muscles used to control the flow of urine from the urinary bladder.

尿道括约肌是用来控制尿液从膀胱流出的肌肉的总称。