What roles do the ureters, bladder, and urethra play in urination?

In the context of the renal system, the ureters, bladder, and urethra function together to transport, store, and eliminate urine from the body.1

• Ureters: These are two narrow, muscular tubes that transport urine from the kidneys to the bladder via peristaltic waves of contraction. Their oblique entry into the bladder wall creates a valvular mechanism that prevents urine from flowing backward into the ureters when the bladder is full.2134
• Bladder: This organ acts as a storage reservoir for urine. Its walls contain the detrusor muscle, which contracts to empty the bladder when it reaches a certain volume.5
• Urethra: This duct conducts urine from the bladder to the exterior of the body. It is held closed by the urethral sphincter to retain urine until voluntary voiding occurs. During urination, the bladder neck and the opening to the urethra relax, allowing the bladder to empty.56

Proper function of these structures is essential; obstructions or infections in these areas can lead to significant complications, including renal system disease.78