<prompt> In a cystometrogram, LaPlaces law has application at:Phase Ia less than 100 mL in bladderPhase Ib 100-400 mL in bladderPhase II more than 450 mL in bladderAll the phases any volume of urine in bladder  <response>: Since bladder is hollow viscous, Laplace law is applicable at any volume in the bladder But to be precise, the real applicability of Laplaces law is in phase-Ib Cystometrogram, is pressure volume relationship in urinary bladder. Phase Ia bladder is filled up to 100ml Phase Ib bladder is filled up to 100-400ml Laplaces law is applicable. From 100-400ml in vol, tension of the bladder wall increases so does the radius, So the pressure remain the same. Beyond that point is Phase II, radius cannot increase fuher but bladder wall tension goes on increasing beyond 400ml thus, pressure increases. 