What serves as a reservoir for urine in the human body?

The urinary bladder serves as the reservoir for urine in the human body. It is a hollow, muscular sac that temporarily holds urine produced by the kidneys before it is excreted. The bladder's structure allows it to expand as it fills with urine and contract when it is emptied during urination. This function is essential for maintaining control over the timing and volume of urine excretion.

In contrast, the kidneys are responsible for filtering blood and producing urine but do not store it. The ureters are the tubes that carry urine from the kidneys to the bladder, and the urethra is the tube through which urine exits the body. Thus, the bladder's primary function as a storage vessel distinguishes it as the correct answer.