AskDefine | Define bladder

Dictionary Definition



1 a distensible membranous sac (usually containing liquid or gas) [syn: vesica]
2 a bag that fills with air

User Contributed Dictionary




  1. A flexible sac that can expand and contract and that holds liquids or gases.
  2. Specifically, the urinary bladder.
  3. A hollow, inflatable organ of a plant.
  4. The inflatable bag inside various balls used in sports, such as footballs and rugby balls.



flexible sac in zoology
urinary bladder
hollow inflatable organ in botany
inflatable bag inside a ball

Extensive Definition

In anatomy, the urinary bladder is a hollow, muscular, and distensible (or elastic) organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination. Urine enters the bladder via the ureters 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.

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 autonomically controlled internal sphincter and the voluntarily controlled external sphincter must be opened. Problems with these muscles can lead to incontinence. If the amount of urine reaches 100% of the urinary bladder volume, the voluntary sphincter becomes involuntary and the urine will be ejected instantly. The body cannot afford having the urinary bladder burst.
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 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.
Since the urinary bladder has a transitional epithelium, compared to the intestine mucosa, the urinary bladder does not produce mucus.


The fundus of the urinary bladder is the superior surface of the bladder. It is lymphatically drained by the external iliac lymph nodes. The peritoneum lies superior to the fundus.

Clinical Significance

  • Cystitis cystica is a chronic cystitis glandularis accompanied by the formation of cysts. This disease can cause chronic urinary tract infections.
  • Interstitial cystitis is a bladder disease of unknown etiology characterized by a bladder wall infiltrated by inflammatory cells resulting in ulcerated mucosa and scarring, spasm of the detrusor muscle, hematuria, urgency, increased frequency, and pain on urination.
  • The bladder may rupture if overfilled and not emptied. This can occur in the case of binge drinkers who have consumed large quantities, but are not conscious due to stupor of the need to urinate. This condition is very rare in women, but does occur. Symptoms include localized pain and uraemia (poisoning due to reabsorbed waste).


See also

External links

Additional images

Image:Illu penis.jpg|Structure of the penis Image:Illu repdt female.jpg|Organs of the female reproductive system. æ. Viewed from behind. | æ seminales. Image:Urinary bladder.JPG|Layers of the urinary bladder wall and cross section of the detrusor muscle.
bladder in Aymara: Yaq'allachi
bladder in Bulgarian: Пикочен мехур
bladder in Catalan: Bufeta urinària
bladder in Czech: Močový měchýř
bladder in Welsh: Pledren
bladder in Danish: Urinblære
bladder in German: Harnblase
bladder in Spanish: Vejiga urinaria
bladder in French: Vessie
bladder in Korean: 방광
bladder in Indonesian: Kandung kemih
bladder in Italian: Vescica urinaria
bladder in Hebrew: שלפוחית השתן
bladder in Latin: Vesica
bladder in Lithuanian: Šlapimo pūslė
bladder in Dutch: Urineblaas
bladder in Japanese: 膀胱
bladder in Norwegian: Urinblære
bladder in Polish: Pęcherz moczowy
bladder in Portuguese: Bexiga
bladder in Quechua: Ispay puru
bladder in Russian: Мочевой пузырь
bladder in Slovak: Močový mechúr
bladder in Slovenian: Sečni mehur
bladder in Finnish: Virtsarakko
bladder in Thai: กระเพาะปัสสาวะ
bladder in Turkish: İdrar kesesi
bladder in Yiddish: בלעדער
bladder in Chinese: 膀胱

Synonyms, Antonyms and Related Words

air bubble, bag, ball, balloon, bleb, blister, blob, blood blister, boll, bolus, bubble, bulb, bulbil, bulblet, bulla, cap and bells, coxcomb, ellipsoid, fever blister, fob, geoid, globe, globelet, globoid, globule, glomerulus, gob, gobbet, knob, knot, motley, oblate spheroid, orb, orbit, orblet, pellet, pocket, poke, prolate spheroid, rondure, sac, sack, slapstick, soap bubble, sock, sphere, spheroid, spherule, vesicle
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