Biomechanics of urinary bladder: slow-filling and slow-emptying cystometry and accommodation.

Maintenance of a tonic accommodated detrusor pressure to a constant or slowly varying volume, obtained by a process of equilibration between passive elongations and active contractions, can be understood as an autonomous potency of a bladder. The earlier presented concept of active accommodation has been validated by the experiments. The pressure-volume relation of the bladder is fundamentally revised. Total volume V can be virtually separated in an elastic volume VE and a plastic or rest volume VR. Both parts change with V and in changing ratio. Tonic pressure marks a border between VE and VR.