Editing Functional: Neural Control of Storage and Voiding (section)

== Bladder mechanics ==

=== Urinary storage (filling) ===
* '''<span style="color:#ff0000">Definition of bladder compliance: change in volume divided by change in intravesical pressure (C = ΔV/ΔP)</span>'''
* '''<span style="color:#ff0000">Decreased compliance of the bladder (steep filling curve) may be the result of impaired (alone or combination) (2):</span>'''
*# '''<span style="color:#ff0000">Viscoelastic properties (3):</span>'''
*## '''Change in composition of the bladder wall (e.g. more collagen, less elastin)'''
*##* Injury, obstruction, or denervation increase collagen content resulting in decreased compliance
*##* '''Types I, III, and IV are the most common types of collagen in the bladder'''
*##** '''When the collagen component of the bladder wall increases, compliance decreases; the poor storage function of poorly compliant bladders is secondary to an alteration in the connective tissue content of the bladder wall, especially increased collagen type III'''
*##*** '''Can occur with chronic inflammation, bladder outlet obstruction, neurologic decentralization (usually at sacral or infrasacral level), and various other types of injury'''
*##*** '''Once decreased compliance occurs because of a replacement by collagen of other components of the stroma, it is generally unresponsive to pharmacologic manipulation, hydraulic distention, or nerve section.''' Most often, under those circumstances, augmentation cystoplasty is required to achieve satisfactory reservoir function.
*##* Bladder muscle hypertrophy, which can result from outlet obstruction, can also result in decreased compliance because hypertrophic muscle is said to be less elastic than normal detrusor.
*##* Once decreased compliance has occurred because of a replacement by collagen of other components of the stroma, it is generally unresponsive to pharmacologic manipulation, hydraulic distention, or nerve section.
*## '''Fast filling rate'''
*##* Filling the bladder at a slow physiologic rate maintains the intravesical pressure <10 cm H2O
*## '''Hyperactivity of the detrusor smooth muscle'''
*# '''<span style="color:#ff0000">Central neural input (inhibition of parasympathetic and activation of sympathetic innervation)</span>'''
* '''Ureteral pressures during bladder filling'''
** '''As the bladder fills, resting pressure within the intravesical ureter increases. This results in an increase in intraluminal (ureteral) pressure and an increase in the frequency of ureteral contractions.''' The end result is continued excretion of urine into the filling bladder.

=== Voiding mechanics (emptying) ===
* '''<span style="color:#ff0000">Intravesical pressure (Pves) reflects the combined factors of abdominal (Pabd) and detrusor (Pdet) pressures. Pdet = Pves – Pabd</span>'''
* '''Low voiding pressure in a females does not necessarily imply impaired detrusor contractility; this may occur in females that are able to open their urethra widely.'''