Which structure is responsible for releasing urine from the bladder?

The urethra is the structure responsible for releasing urine from the bladder. It is a muscular tube that connects the bladder to the external opening, allowing urine to exit the body during urination. The urethra plays a crucial role in the urinary system by ensuring that urine can be expelled efficiently and at the appropriate time.

The ureter, in contrast, is a tube that carries urine from the kidneys to the bladder, serving as a conduit rather than a release pathway. The kidneys are responsible for filtering blood and producing urine, but they do not facilitate its release. The urethral sphincter, while it regulates the flow of urine through the urethra and maintains continence, does not itself release urine; it works in conjunction with the urethra to control urination. Thus, the urethra is key to the process of urination as it is the final pathway through which urine is expelled from the bladder.