• Chinese: 氣囊
• Finnish: rakko

• Chinese: 球膽

Derived terms

• air bladder
• bladdered
• bladderwrack
• gall bladder
• gas bladder
• shy bladder
• swim bladder
• urinary bladder

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.

Fundus

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).

Notes

See also

• Artificial bladder
• Bladder cancer
• Bladder spasm
• 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 stones.
• Neurogenic bladder
• Ureterocele
• Urinary incontinence
• Urodynamics The study of the functional aspects of the detrusor muscle.
• Uvula of urinary bladder
• Vesicouretic reflux

External links

• "Urinary Bladder"
• - "Mammal, bladder (LM, Medium)"
• - "The Female Pelvis: The Urinary bladder"
• - "The Male Pelvis: The Urinary bladder"
• Bladder pain and interstitial cystitis details
• Overactive bladder -article

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.

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