Editing Urination (section)

====Voluntary control====
{{multiple image
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| image1            = Red Deer Stag scenting itself with urine during the rut - Bushy Park (45123184221).jpg
| image2            = Deer peeing.jpg
| footer            = [[Deer]] urinate in a standing or squatting position.<ref>Müller-Schwarze, Dietland. "Pheromones in black-tailed deer (Odocoileus hemionus columbianus)." Animal Behaviour 19.1 (1971): 141-152.</ref><ref>Moore, W. GERALD, and R. LARRY Marchinton. "Marking behavior and its social function in white-tailed deer." The behaviour of ungulates and its relation to management 1 (1974): 447-456.</ref><ref>{{cite journal | last1 = Lincoln | first1 = G. A. | year = 1971 | title = The seasonal reproductive changes in the red deer stag (Cervus elaphus) | journal = Journal of Zoology | volume = 163 | issue = 1| pages = 105–123 | doi=10.1111/j.1469-7998.1971.tb04527.x }}</ref>
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The mechanism by which voluntary urination is initiated remains unsettled.<ref>{{cite journal |vauthors=DasGupta R, Kavia RB, Fowler CJ | title = Cerebral mechanisms and voiding function | journal = BJU Int. | volume = 99 | issue = 4 | pages = 731–4 | year = 2007 | pmid = 17378838 | doi = 10.1111/j.1464-410X.2007.06749.x | s2cid = 12318860 | doi-access =  }}</ref> One possibility is that the voluntary relaxation of the muscles of the pelvic floor causes a sufficient downward tug on the [[detrusor muscle]] to initiate its contraction.<ref>{{cite journal |last1=Kinder |first1=MattiV. |last2=Bastiaanssen |first2=EricaH.C. |last3=Janknegt |first3=RuudA. |last4=Marani |first4=Enrico |title=Neuronal circuitry of the lower urinary tract; central and peripheral neuronal control of the micturition cycle |journal=Anatomy and Embryology |date=September 1995 |volume=192 |issue=3 |pages=195–209 |doi=10.1007/BF00184744 |pmid=8651504 }}</ref> Another possibility is the excitation or disinhibition of neurons in the pontine micturition center, which causes concurrent contraction of the bladder and relaxation of the sphincter.<ref name="yoshimura" />

There is an inhibitory area for micturition in the midbrain. After transection of the brain stem just above the pons, the threshold is lowered and less bladder filling is required to trigger it, whereas after transection at the top of the midbrain, the threshold for the reflex is essentially normal. There is another facilitatory area in the posterior hypothalamus. In humans with lesions in the superior frontal gyrus, the desire to urinate is reduced and there is also difficulty in stopping micturition once it has commenced. However, stimulation experiments in animals indicate that other cortical areas also affect the process.

The bladder can be made to contract by voluntary facilitation of the spinal voiding reflex when it contains only a few milliliters of urine. Voluntary contraction of the [[abdominal muscles]] aids the expulsion of urine by increasing the pressure applied to the urinary bladder wall, but voiding can be initiated without straining even when the bladder is nearly empty.
Voiding can also be consciously interrupted once it has begun, through a contraction of the perineal muscles. The external sphincter can be contracted voluntarily, which will prevent urine from passing down the urethra.