View source for Urinary bladder

{{Infobox Anatomy |
 Name = Urinary bladder |
 Latin = vesica urinaria |
 GraySubject = 255 |
 GrayPage = 1227 |
 Image  = Illu urinary system.jpg |
 Caption  = Urinary system. |
 Image2 = Illu_bladder.jpg |
 Caption2 = Bladder |
 Width = 300 |
 System = |
 Artery = [[Superior vesical artery]]<BR>[[Inferior vesical artery]]<BR>[[Umbilical artery]]<BR>[[Vaginal artery]] |
 Vein = [[Vesical venous plexus]] |
 Nerve = [[Vesical nervous plexus]] |
 Lymph = [[external iliac lymph nodes]], [[internal iliac lymph nodes]] |
 Precursor = [[urogenital sinus]] |
 MeshName = Bladder |
 MeshNumber = A05.810.161 |
 DorlandsPre = v_07 |
 DorlandsSuf = 12855244 |
}}
{{Search infobox}}
{{SCC}}

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==Overview==

In [[anatomy]], the '''urinary bladder''' is a hollow, muscular, and distensible (or elastic) organ that sits on the [[pelvic floor]] in [[mammal]]s. It is the organ that collects [[urine]] excreted by the [[kidney]]s prior to disposal by [[urination]]. Urine enters the bladder via the [[ureter]]s and exits via the [[urethra]].

In males, the bladder is superior to the [[prostate]], and separated from the [[rectum]] by the [[rectovesical excavation]].

In females, the bladder is separated from the [[rectum]] by the [[rectouterine excavation]], and it is separated from the [[uterus]] by the [[vesicouterine excavation]].

==Regions==   
* [[Trigone of urinary bladder]]: The [[ureters]] enter the bladder diagonally from its dorsolateral floor in an area called the [[trigone_of_urinary_bladder|trigone]], which is a triangular shaped area on the postero-inferior wall of the bladder. The [[urethra]] exits at the lowest point of the triangle of the trigone.   
* Apex: The [[Median umbilical ligament]] connects to the apex of the bladder.   
* Neck: The Neck is connected to the [[pubic bone]] by the pubovesical ligament in women, and by the puboprostatic ligament in men.   
   
==Wall==   
The wall of the urinary bladder consists of three layers:    
    
* [[Mucosa]]: in this instance [[transitional epithelium]] & [[lamina propria]]   
* Detrusor muscle: consists of an inner and outer longitudinal layer and a middle circular layer of [[smooth muscle]]    
* a fibrous [[adventitia]] and the [[visceral peritoneum]]: lie on superior surface

== Detrusor muscle ==

The detrusor muscle is a layer of the urinary bladder wall made of [[smooth muscle]] fibers arranged in spiral, longitudinal, and circular bundles. When the bladder is stretched, this signals the [[parasympathetic]] nervous system to contract the [[detrusor muscle]]. This encourages the bladder to expel [[urine]] through the [[urethra]]. 

For the urine to exit the bladder, both the [[autonomic|autonomically]] controlled internal [[sphincter]] and the [[somatic|voluntarily]] controlled external sphincter must be opened. Problems with these muscles can lead to [[Urinary incontinence|incontinence]]. 

The urinary bladder usually holds 400–620 mL of urine, but it can hold twice this without rupturing if, for example, the outflow is obstructed.  

The desire to [[Urination|urinate]] usually starts when the bladder reaches around 75% of its working volume. If the subject is distracted the desire can fade and return with more urgency as the bladder continues to fill.

==See also==

* [[Artificial bladder]]
* [[Bladder cancer]]
* [[Bladder sphincter dyssynergia]], a condition in which the sufferer cannot coordinate relaxation of the urethra sphincter with the contraction of the bladder muscles
* [[Cystitis]]
* [[Hematuria]], or presence of blood in the urine, is a reason to seek medical attention without delay, as it is a symptom of bladder cancer as well as bladder and [[kidney stone]]s.
* [[Neurogenic bladder]]
* [[Ureterocele]]
* [[Urinary incontinence]]
* [[Urodynamics]] The study of the functional aspects of the detrusor muscle.
* [[Uvula of urinary bladder]]
* [[Vesicouretic reflux]]

==External links==
* {{KansasHistology|epithel|epith09}} "Urinary Bladder"
* {{UCDavisOrganology|Urinary/mammal/bladder/bladder1}} - "Mammal, bladder (LM, Medium)"
* {{IowaHistologyInteractive|445}}
* {{SUNYAnatomyLabs|43|07|01|00}} - "The Female Pelvis: The Urinary bladder"
* {{SUNYAnatomyLabs|44|04|01|03}} - "The Male Pelvis: The Urinary bladder"

==Additional images==
<gallery>
 Image:Illu penis.jpg|Structure of the penis
 Image:Illu repdt female.jpg|Organs of the female reproductive system.
 Image:Gray402.png|Coronal section of pelvis, showing arrangement of fasciæ. Viewed from behind. 
 Image:Gray829.png|Dissection of side wall of pelvis showing sacral and pudendal plexuses. (Bladder visible at lower left.) |
 Image:Gray1037.png|The peritoneum of the male pelvis.
 Image:Gray1135.png|Median sagitta section of male pelvis.
 Image:Gray1136.png|Male pelvic organs seen from right side.
 Image:Gray1139.png|Median sagittal section of female pelvis.
 Image:Gray1140.png|The interior of bladder.
 Image:Gray1141.png|Vertical section of bladder wall. 
 Image:Gray1152.png|Fundus of the bladder with the vesiculæ seminales.
 Image:Gray1156.png|Vertical section of bladder, penis, and urethra.
 Image:Gray1165.png|Female pelvis and its contents, seen from above and in front.
 Image:Gray1224.png|Topography of thoracic and abdominal viscera.
 Image:Penis.svg|The bladder can be seen highlighted in yellow in the illustration.
 Image:Urinary bladder.JPG|Layers of the urinary bladder wall and cross section of the detrusor muscle.
</gallery>

{{urinary system}}
{{SIB}}

[[Category:Pelvis]]
[[Category:Organs]]
[[Category:Urology]]
[[Category:Urinary system]]

{{Link FA|de}}

[[bg:Пикочен мехур]]
[[cs:Močový měchýř]]
[[cy:Pledren]]
[[da:Urinblære]]
[[de:Harnblase]]
[[es:Vejiga urinaria]]
[[fr:Vessie]]
[[id:Kandung kemih]]
[[he:שלפוחית השתן]]
[[it:Vescica urinaria]]
[[lt:Šlapimo pūslė]]
[[nl:Urineblaas]]
[[ja:膀胱]]
[[no:Urinblære]]
[[pl:Pęcherz moczowy]]
[[pt:Bexiga]]
[[ru:Мочевой пузырь]]
[[sk:Močový mechúr]]
[[fi:Virtsarakko]]
[[sv:Urinblåsa]]
[[zh:膀胱]]
[[yi:בלעדער]]

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