(1) A longitudinal contraction ring preceding the circumferential one axially distends the distal segments. (2) Initial phase of the longitudinal contraction ring promotes bolus volume rearrangement toward the passive diameter dilation. (3) Longitudinal contraction with the maximum circumferential contraction ring just behind it helps pushing the urine bolus downward. (4) Ureteral segments proximal to the longitudinal contraction ring will be passively axially stretched which also helps their filling.