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How do ureters transport urine from the kidneys to the bladder?

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Human kidneys — renal system Diagram showing the location of the kidneys in the abdominal cavity and their attachment to major arteries and veins.

The ureters transport urine from the kidneys to the urinary bladder primarily through peristaltic movements.12

These movements consist of periodic, wavelike contractions of the smooth muscle fibers located in the intermediate layer of the ureteric wall. This muscular coat is organized into longitudinal and circular layers that work to push urine downward from the renal pelvis into the bladder.12

The structure of the ureter supports this process in several ways:
* Contractile Walls: The thick, involuntary muscle fibers provide the necessary force for propulsion.32
* Dilation: The mucous membrane lining is arranged in longitudinal folds, which allow the channel to expand as needed.2
* Impermeability: The lining is impermeable to the substances found in urine, ensuring that fluids are not absorbed through the walls during transport.1

As the ureters reach the bladder, they pass through the bladder wall in a manner that causes the terminal portion to close as the bladder fills, preventing the backflow of urine.3