Answer Happy

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Option 2- stretches/compreses
Option 3- closed/open
How does the anatomy of the ureters with respect to the urinary bladder prevent the spread of infections from the lower urinary tract to the upper urinary tract? The ureters drain anteriorly into the inferior urinary bladder. As each ureter passes along the [Select] urinary bladder, it passes through a tunnel in the bladder wall. As urine collects in the bladder, the pressure rises and [ Select ] pinches the ureters [ Select] the tunnels, which . This prevents backflow from the bladder to the [Select] , protecting them from infections that could spread from the lower urinary tract.