urinary bladder

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Related to Bladder diseases: interstitial cystitis, Bladder cancer, Kidney diseases

urinary bladder

a distensible membranous sac in which the urine excreted from the kidneys is stored

Urinary Bladder

 

the organ in which urine accumulates before being excreted from the body in certain invertebrates, in most vertebrates, and in man.

The urinary bladder takes several forms in invertebrates: rotifers have an unpaired bladder, oligochaetes and hirudineans (leeches) have multiple bladders, and higher crustaceans have paired bladders. In the vertebrates, the urinary bladder is usually unpaired. In female elasmobranchs, paired urinary bladders, or urinary sinuses, occur as widenings of the ureters; these sinuses merge in the posterior end of the body into an unpaired urinary sinus that opens into the cloaca. In most teleosts, the urinary bladder occurs as a widening of the ureters that merge into a terminal unpaired duct; this duct can have its own external orifice, or it can share an orifice with the terminal sections of the gonaducts in males of certain species.

In most terrestrial vertebrates, the urinary bladder is formed from the embryonic membrane called the allantois; amphibians are the only class in which the bladder arises from a ventral diverticulum of the cloaca. In amphibians, reptiles, and monotremes, the urinary bladder opens into the cloaca opposite the cloacal openings of the ureters. In metatherians (marsupials) and eutherians (placental mammals), the ureters empty directly into the urinary bladder, which in turn is usually connected to the exterior by the urethra. The ureters empty into the urogenital sinus only in the females of certain animals. Birds have no urinary bladder, and crocodilians and Serpentes (snakes) are the only reptiles in which this structure is rudimentary.

In man, the urinary bladder is a hollow, muscular organ situated in the lesser pelvis. Its average capacity is 500 cc, but when distended, it can hold much more urine. The bladder’s walls are lined with mucosa. Urine passes through the ureters from the kidneys and is deposited into the urinary bladder every 10–20 seconds. The neck of the urinary bladder opens into the first section of the urethra; ring-shaped muscles are located in the neck and form two sphincters that surround and close the urethra. Contraction of the sphincters prevents the urine from flowing out of the bladder. When the bladder is full, neural elements in the bladder wall elicit reflex contractions of the bladder muscles, as well as relaxation of the sphincteral muscles; these simultaneous processes result in the outflow of urine through the urethra.

In males, the posterior wall of the bladder is adjacent to the rectum; the neck of the bladder and the first section of the urethra are surrounded by the prostate gland. Diseases of the prostate can interfere with and even prevent urination. In females, the posterior wall of the bladder is adjacent to the uterine cervix and to the vagina.

The mucous membrane of the bladder is extremely susceptible to infection. The short length of the female urethra facilitates the spread of infections from the genitalia to the bladder. In males, the bladder can become infected because of an impairment in the excretory function, as occurs in diseases of the prostate.

urinary bladder

[′yu̇r·ə‚ner·ē ′blad·ər]
(anatomy)
A hollow organ which serves as a reservoir for urine.
References in periodicals archive ?
TARIS Biomedical[R] is a clinical stage specialty pharmaceutical company focused on developing a pipeline of innovative treatments for bladder diseases.
In addition to Interstitial Cystitis, TARIS[TM] is developing a pipeline of novel, targeted therapies designed to treat a variety of bladder diseases, such as bladder cancer and urinary incontinence, utilizing its novel targeted bladder delivery system.
TARIS is initially focused on treating disorders of the genitourinary system, specifically the treatment of bladder diseases.
TARIS is developing a pipeline of novel, targeted therapies designed to treat a variety of bladder diseases with high unmet medical need, which leverages common, minimally-invasive urologic procedures to deliver and maintain drug directly to target tissues.
TARIS Biomedical is developing several drug-device convergence product opportunities focused on addressing underserved disease areas, with an initial focus on the genitourinary system, specifically for the treatment of bladder diseases.
It validates the core platform technology and opens up the potential of this drug-device convergence system, beyond IC, into a variety of bladder diseases such as bladder cancer and overactive bladder," said Robert S.
Bladder diseases, which are difficult to treat with systemic therapies, affect 50 million people in the U.
TARIS Biomedical, a cutting-edge biotechnology company based in Boston, USA, has invented a technology that can control bladder diseases to a great extent.