[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Physiology](https://durgical.com/en/physiology/) › [Renal, fluids and acid–base](https://durgical.com/en/physiology/areas/renal/) › Urine transport: ureter peristalsis and bladder filling

# Urine transport: ureter peristalsis and bladder filling

- Mechanism
- For completeness

Waves of muscle squeeze urine down the ureters; the bladder stretches to hold it with little rise in pressure until it is nearly full.

Updated Nov 13, 2026

Also called: Cystometrogram, Ureterorenal reflex, Vesicoureteral valve

**See it in 3D:** [Renal pelvis](https://durgical.com/en/anatomy/renal-pelvis/) · [Ureters](https://durgical.com/en/anatomy/ureter/) · [Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/) · [Trigone of bladder](https://durgical.com/en/anatomy/trigone-of-bladder/)

## Key points

- Ureteral peristalsis is myogenic, started by stretch of the calyces and pelvis; nerves only modulate it (parasympathetic ↑, sympathetic ↓).
- The oblique path through the detrusor compresses the ureter when bladder pressure rises: a functional valve against vesicoureteral reflux.
- A short intramural ureter (congenital) causes vesicoureteral reflux, upper urinary tract infection and renal scarring in children.
- A stone triggers intense ureteral spasm and colicky pain; the ureterorenal reflex constricts afferent arterioles and lowers urine flow from that kidney.
- Cystometrogram: an early small rise, a long flat plateau (accommodation), then a steep rise near capacity; reflex detrusor waves are superimposed.

## What it is

Urine does not fall to the bladder by gravity: smooth-muscle waves started by pacemaker cells in the calyces and pelvis push it down the ureter. The ureter crosses the bladder wall obliquely, which makes a flap valve against reflux. The bladder then fills at low pressure because its wall relaxes as it stretches; pressure rises steeply only near capacity, as shown on the cystometrogram.

## How it works, step by step

- Urine from the collecting ducts stretches the calyces and pelvis; pacemaker cells there fire faster.
- A peristaltic wave spreads down the ureter, a few times per minute, carrying a bolus of urine.
- At the bladder, the ureter runs obliquely through the detrusor for 1–2 cm before opening at the trigone.
- Bladder filling and voiding raise intravesical pressure, which flattens the intramural ureter and blocks backflow.
- The bladder wall (smooth muscle, stress relaxation) stretches with little rise in pressure while volume rises to a few hundred mL.
- Near ≈ 300–400 mL, wall tension and pressure climb fast; stretch receptors send stronger signals and micturition waves become frequent.
- A ureteric stone stretches the ureter: pain fibres (T11–L2) give colic that radiates to the groin, and a sympathetic reflex constricts renal arterioles.

## Approximate values (adult)

| Parameter | Value | Note |
| --- | --- | --- |
| First desire to void | ≈ 150–250 mL | |
| Usual capacity | ≈ 400–500 mL | |
| Bladder pressure during filling | ≈ 5–15 cmH₂O | stays low until near capacity |
| Intramural ureter length | ≈ 1–2 cm | shorter in reflux |
| Residual volume after voiding |
- Renal colic: waves of severe flank pain as peristalsis pushes against a stone; distension above it gives hydronephrosis.
- Bilateral obstruction (or one kidney) gives anuria and postrenal acute kidney injury; the ureterorenal reflex lowers flow on the blocked side.
- Urodynamics: a steep early curve means a small, poorly compliant bladder (neurogenic or fibrotic); unprovoked detrusor waves during filling mean detrusor overactivity.
- A non-compliant, high-pressure bladder transmits pressure to the ureters and can damage the kidneys even without reflux.

## Memory aid

Ureter = toothpaste tube squeezed from the top; its bladder entry = a door that the full room pushes shut.

## Test yourself

Think of the answer, then tap the question to see it.

## What prevents urine from flowing back up the ureter when the bladder contracts?

The ureter crosses the detrusor obliquely; rising bladder pressure compresses the intramural segment, acting as a flap valve.

## Why does a ureteric stone lower urine output from the affected kidney even before the pelvis fills?

Pain impulses trigger a sympathetic ureterorenal reflex that constricts renal arterioles and lowers GFR on that side, besides the back-pressure on filtration.

## On a normal cystometrogram, why does pressure stay almost flat between about 100 and 300 mL?

The smooth-muscle wall relaxes as it stretches (stress relaxation) and the bladder unfolds, so volume rises with little rise in pressure (high compliance).

## A child has recurrent pyelonephritis and a short intramural ureter. What is the link?

The short segment fails as a valve, so infected bladder urine refluxes up to the kidney during voiding (vesicoureteral reflux).

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## Connections

## See it in 3D 4

The structures of Durgical's 3D anatomy where it happens.

- [Renal pelvis](https://durgical.com/en/anatomy/renal-pelvis/)
- [Ureters](https://durgical.com/en/anatomy/ureter/)
- [Urinary bladder](https://durgical.com/en/anatomy/urinary-bladder/)
- [Trigone of bladder](https://durgical.com/en/anatomy/trigone-of-bladder/)

## Related topics 1

- [Micturition and the bladder reflex](https://durgical.com/en/physiology/micturition-and-the-bladder-reflex/)

## Related conditions 4

- [Kidney stones (urolithiasis)](https://durgical.com/en/conditions/kidney-stones/)
- [Vesicoureteral reflux](https://durgical.com/en/conditions/vesicoureteral-reflux/)
- [Hydronephrosis and obstructive uropathy](https://durgical.com/en/conditions/hydronephrosis-and-obstructive-uropathy/)
- [Overactive bladder and urge incontinence](https://durgical.com/en/conditions/overactive-bladder-and-urge-incontinence/)

[← All of physiology](https://durgical.com/en/physiology/)

Educational physiology content; not a diagnostic or treatment guide and no substitute for a health professional's advice. Values are approximate references. No doses are given.

Sources: [Anatomy, Abdomen and Pelvis Ureter](https://www.ncbi.nlm.nih.gov/books/NBK532980/) (StatPearls (NCBI Bookshelf), 2025); [Anatomy, Abdomen and Pelvis: Bladder](https://www.ncbi.nlm.nih.gov/books/NBK531465/) (StatPearls (NCBI Bookshelf), 2025); [Renal Calculi, Nephrolithiasis](https://www.ncbi.nlm.nih.gov/books/NBK442014/) (StatPearls (NCBI Bookshelf), 2025); [Kidney stones: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000458.htm) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/physiology/urine-transport-ureter-peristalsis-and-bladder-filling/