This tube runs from the bottom of the bladder to the outside of the body.
In males the urethra is approximately 8 inches long and leaves the
bladder, passing downward through the prostate gland, through the
length of the penis until it ends at the urethral orifice or opening at the
tip of the glans penis. In females, the tube is around 4 – 5 cm in length
and exits the body just in front of the vagina/penis.

A ring like band of muscle, called the internal urethral sphincter helps
control the process of urination. This sphincter is an involuntary muscle
and therefore requires no participant control. The external sphincter,
lying below the internal sphincter is made up of smooth and striated
muscle and is under the control of the pudendal nerve.