Final answer:
The main areas of ureter constriction are the ureteropelvic junction and the ureterovesical junction, which are critical points for urine flow from kidneys to bladder.
Step-by-step explanation:
Main Areas of Ureter Constriction
The main areas of ureter constriction are the ureteropelvic junction, where the ureters leave the kidney, and the ureterovesical junction, where the ureters enter the bladder. At these points, the ureters are narrow, creating potential sites for obstruction or constriction. These areas are critical in the propulsion of urine from the kidneys to the bladder, utilizing waves of peristalsis. Notably, at the ureterovesical junction, the ureters enter the bladder wall obliquely to function as a one-way valve, preventing the backflow of urine, a condition that could lead to complications such as vesicoureteral reflux. Understanding the anatomy and physiology of these constriction points can be important for diagnosing and treating urinary tract issues.