Editing Bladder

{{Short description|Organ in vertebrates that collects and stores urine from the kidneys before disposal}}
{{About|urinary bladders}}
{{Infobox anatomy
| Name        = Bladder
| Latin       = vesica urinaria
| Image       = Urinary_system.svg
| Caption     = 1. ''Human [[urinary system]]:'' 2. [[Kidney]], 3. [[Renal pelvis]], 4. [[Ureter]], '''5'''. '''Bladder''', 6. [[Urethra]]. (Left side with [[Frontal plane#Planes|frontal section]])<br /> 7. [[Adrenal gland]]<br /> ''Vessels:'' 8. [[Renal artery]] and [[Renal vein|vein]], 9. [[Inferior vena cava]], 10. [[Abdominal aorta]], 11. [[Common iliac artery]] and [[Common iliac vein|vein]]<br /> ''With transparency:'' 12. [[Liver]], 13. [[Large intestine]], 14. [[Pelvis]]
| Width       = 300
| Image2      = 
| Caption2    = 
| Precursor   = [[Urogenital sinus]]
| System      = [[Urinary system]]
| Artery      = [[Superior vesical artery]]<br />[[inferior vesical artery]]<br />[[umbilical artery]]<br />[[vaginal artery]], [[internal pudendal artery]], [[deep external pudendal artery]]
| Vein        = [[Vesical venous plexus]]
| Nerve       = [[Vesical nervous plexus]], [[pudendal nerve]]
| Lymph       =Preaortic lymph nodes 
}}

The '''bladder''' ({{Etymology|ang|blædre|bladder, [[blister]], [[pimple]]}}) is a [[hollow organ]] in [[human]]s and other [[vertebrate]]s that stores [[urine]] from the [[Kidney (vertebrates)|kidneys]]. In [[placental mammals]], urine enters the bladder via the [[ureter]]s and exits via the [[urethra]] during [[urination]].<ref name="Wake1992">{{cite book|author=Marvalee H. Wake|title=Hyman's Comparative Vertebrate Anatomy|url=https://books.google.com/books?id=VKlWjdOkiMwC&pg=PA583|access-date=6 May 2013|date=15 September 1992|publisher=University of Chicago Press|isbn=978-0-226-87013-7|pages=583}}</ref><ref>{{Cite journal |last=Brading |first=Alison F. |date=January 1999 |title=The physiology of the mammalian urinary outflow tract |url=https://physoc.onlinelibrary.wiley.com/doi/10.1111/j.1469-445X.1999.tb00084.x |journal=Experimental Physiology |language=en |volume=84 |issue=1 |pages=215–221 |doi=10.1111/j.1469-445X.1999.tb00084.x |pmid=10081719 |issn=0958-0670}}</ref> In humans, the bladder is a distensible organ that sits on the [[pelvic floor]]. The typical adult human bladder will hold between 300 and {{nowrap|500 ml}} (10 and {{nowrap|17 fl oz}}) before the urge to empty occurs, but can hold considerably more.<ref name="medphys">{{cite book|last1=Boron|first1=Walter F.|last2=Boulpaep|first2=Emile L.|title=Medical Physiology|date=2016|publisher=Elsevier Health Sciences|isbn=9781455733286|page=738|url=https://books.google.com/books?id=6QzhCwAAQBAJ&pg=PA738|access-date=1 June 2016}}</ref><ref name="Cardozo99">{{cite book|last1=Walker-Smith|first1=John|last2=Murch|first2=Simon|editor1-last=Cardozo|editor1-first=Linda|title=Diseases of the Small Intestine in Childhood|date=1999|publisher=CRC Press|isbn=9781901865059|page=16|edition=4|url=https://books.google.com/books?id=EMMUyiKOOiEC&pg=PA16|access-date=1 June 2016}}</ref>

The Latin phrase for "urinary bladder" is ''vesica urinaria'', and the term ''vesical'' or prefix ''vesico-'' appear in connection with associated structures such as [[vesical veins]]. The modern Latin word for "bladder" – ''cystis'' – appears in associated terms such as [[cystitis]] (inflammation of the bladder).

==Structure==
{{Further|Urination#Anatomy of the bladder and outlet}}
[[File:Position of the urinary bladder 1.png|thumb|Male and female urinary bladders in lateral cross-section]]

In humans, the bladder is a hollow muscular organ situated at the base of the [[pelvis]]. <!-- Shape -->In [[gross anatomy]], the bladder can be divided into a broad {{wt|en|fundus}} (base), a body, an apex, and a neck.<ref name="Netter" /> The apex (also called the vertex) is directed forward toward the upper part of the [[pubic symphysis]], and from there the [[median umbilical ligament]] continues upward on the back of the anterior abdominal wall to the [[Navel|umbilicus]]. The [[peritoneum]] is carried by it from the apex on to the [[abdominal wall]] to form the [[middle umbilical fold]]. The neck of the bladder is the area at the base of the [[trigone of the urinary bladder|trigone]] that surrounds the [[internal urethral orifice]] that leads to the urethra.<ref name="Netter">{{cite book|last1= Netter|first1= Frank H.|title= Atlas of Human Anatomy Including Student Consult Interactive Ancillaries and Guides|date= 2014|publisher= W B Saunders Co|location= Philadelphia, Penn.|isbn= 978-14557-0418-7|pages= 346–8|edition= 6th}}</ref> In males, the neck of the urinary bladder is next to the [[prostate gland]].

<!-- Openings -->The bladder has three openings. The two [[ureter]]s enter the bladder at [[Ureter#Structure|ureteric orifices]], and the [[urethra]] enters at the [[Trigone of the urinary bladder|trigone of the bladder]]. These ureteric openings have mucosal flaps in front of them that act as valves in preventing the backflow of urine into the ureters,<ref name="SEER">{{cite web|title= SEER Training:Urinary Bladder|url= https://training.seer.cancer.gov/anatomy/urinary/components/bladder.html|website= training.seer.cancer.gov|language= en}}</ref> known as [[vesicoureteral reflux]]. Between the two ureteric openings is a raised area of tissue called the interureteric crest.<ref name="Netter" /> This makes the upper boundary of the trigone. The trigone is an area of [[smooth muscle]] that forms the floor of the bladder above the urethra.<ref name="Viana">{{cite journal | vauthors = Viana R, Batourina E, Huang H, Dressler GR, Kobayashi A, Behringer RR, Shapiro E, Hensle T, Lambert S, Mendelsohn C | title = The development of the bladder trigone, the center of the anti-reflux mechanism | journal = Development | volume = 134 | issue = 20 | pages = 3763–9 | date = October 2007 | pmid = 17881488 | doi = 10.1242/dev.011270| doi-access = free }}</ref> It is an area of smooth tissue for the easy flow of urine into and from this part of the bladder - in contrast to the irregular surface formed by the rugae.

<!-- Walls -->The walls of the bladder have a series of ridges, thick mucosal folds known as [[rugae]] that allow for the expansion of the bladder. The [[detrusor muscle]] is the muscular layer of the wall made of [[smooth muscle]] [[muscle fibers|fibers]] arranged in spiral, longitudinal, and circular bundles.<ref name="Wheaters2013" /> The detrusor muscle is able to change its length. It can also contract for a long time whilst [[urination|voiding]], and it stays relaxed whilst the bladder is filling.<ref name="Andersson">{{cite journal | vauthors = Andersson KE, Arner A | title = Urinary bladder contraction and relaxation: physiology and pathophysiology | journal = Physiol. Rev. | volume = 84 | issue = 3 | pages = 935–86 | date = July 2004 | pmid = 15269341 | doi = 10.1152/physrev.00038.2003 | citeseerx = 10.1.1.324.7009 }}</ref> The wall of the urinary bladder is normally 3–5&nbsp;mm thick.<ref name="Patel2010" /> When well distended, the wall is normally less than 3&nbsp;mm.

=== Nearby structures ===
[[File:Prostatelead.jpg|thumb|240px|Bladder location and associated structures in the male]]

In males, the [[Prostate|prostate gland]] lies outside the opening for the urethra. The middle lobe of the prostate causes an elevation in the mucous membrane behind the internal urethral orifice called the uvula of urinary bladder. The uvula can enlarge when the prostate becomes enlarged.

The bladder is located below the [[peritoneal cavity]] near the [[pelvic floor]] and behind the [[pubic symphysis]]. In males, it lies in front of the rectum, separated by the [[rectovesical pouch]], and is supported by fibres of the [[levator ani]] and of the prostate gland. In females, it lies in front of the [[uterus]], separated by the [[vesicouterine pouch]], and is supported by the elevator ani and the upper part of the [[vagina]].<ref name=Patel2010>[https://books.google.com/books?id=Z4t3dnDR1e8C&pg=PA12 Page 12] in: {{cite book|title= Imaging and Urodynamics of the Lower Urinary Tract|author= Uday Patel|publisher= Springer Science & Business Media|year= 2010|isbn= 9781848828360}}</ref>

===Blood and lymph supply===
The bladder receives blood by the [[vesical arteries]] and drained into a network of [[vesical veins]].<ref name="Grays2016" /> The [[superior vesical artery]] supplies blood to the upper part of the bladder. The lower part of the bladder is supplied by the [[inferior vesical artery]], both of which are branches of the [[internal iliac arteries]].<ref name="Grays2016" /> In females, the [[uterine arteries|uterine]] and [[vaginal arteries]] provide additional blood supply.<ref name="Grays2016" /> Venous drainage begins in a network of small vessels on the lower {{wt|en|lateral}} surfaces of the bladder, which coalesce and travel with the lateral ligaments of the bladder into the [[internal iliac vein]]s.<ref name="Grays2016" />

The [[lymphatic system|lymph]] drained from the bladder begins in a series of networks throughout the mucosal, muscular and serosal layers. These then form three sets of vessels: one set near the trigone draining the bottom of the bladder; one set draining the top of the bladder; and another set draining the outer undersurface of the bladder. The majority of these vessels drain into the [[external iliac lymph nodes]].<ref name="Grays2016" />

=== Nerve supply ===
The bladder receives both sensory and motor supply from [[sympathetic nervous system|sympathetic]] and the [[parasympathetic nervous system]]s.<ref name="Grays2016" /> The motor supply from both sympathetic fibers, most of which arise from the [[superior hypogastric plexus|superior]] and [[inferior hypogastric plexus]]es and nerves, and from parasympathetic fibers, which come from the [[pelvic splanchnic nerves]].<ref name="Moore227">{{cite book|last= Moore|first= Keith|title= Essential Clinical Anatomy, Third Edition|year= 2007|publisher= Lippincott Williams & Wilkins|isbn= 978-0-7817-6274-8|pages= 227–228|author2= Anne Agur }}</ref>

Sensation from the bladder, relating to distension or to irritation (such as by infection or a stone) is transmitted primarily through the parasympathetic nervous system.<ref name="Grays2016" /> These travel via [[sacral nerves]] to [[sacral nerve roots|S2-4]].<ref name=Ganong2019 /> From here, sensation travels to the [[human brain|brain]] via the [[dorsal columns]] in the [[spinal cord]].<ref name=Grays2016 />

===Microanatomy===
When [[Histology|viewed under a microscope]], the bladder can be seen to have an inner lining (called [[epithelium]]), three layers of muscle fibres, and an outer [[adventitia]].<ref name=Wheaters2013 >{{cite book |last1=Young |first1=Barbara |last2=O'Dowd |first2=Geraldine |last3=Woodford |first3=Phillip |title=Wheater's functional histology: a text and colour atlas.|publisher=Elsevier |location=Philadelphia |date=2013|isbn=9780702047473 |edition=6th|chapter=Urinary system|pages=315–7}}</ref>

The inner wall of the bladder is called [[urothelium]], a type of [[transitional epithelium]] formed by three to six layers of cells; the cells may become more cuboidal or flatter depending on whether the bladder is empty or full.<ref name=Wheaters2013 /> Additionally, these are lined with a [[mucous membrane]] consisting of a surface [[glycocalyx]] that protects the cells beneath it from urine.<ref name="Urothelium">{{cite journal |last1=Stromberga |first1=Z |last2=Chess-Williams |first2=R |last3=Moro |first3=C |title=Histamine modulation of urinary bladder urothelium, lamina propria and detrusor contractile activity via H1 and H2 receptors. |journal=Scientific Reports |date=7 March 2019 |volume=9 |issue=1 |pages=3899 |doi=10.1038/s41598-019-40384-1 |pmid=30846750|pmc=6405771 |bibcode=2019NatSR...9.3899S }}</ref> The epithelium lies on a thin [[basement membrane]], and a [[lamina propria]].<ref name=Wheaters2013 /> The mucosal lining also offers a urothelial barrier against the passing of infections.<ref name="Janssen">{{cite journal|last1= Janssen|first1= DA|title= The distribution and function of chondroitin sulfate and other sulfated glycosaminoglycans in the human bladder and their contribution to the protective bladder barrier.|journal= The Journal of Urology|date= January 2013|volume= 189|issue= 1|pages= 336–42|pmid= 23174248|doi=10.1016/j.juro.2012.09.022}}</ref>

These layers are surrounded by three layers of muscle fibres arranged as an inner layer of fibres orientated longitudinally, a middle layer of circular fibres, and an outermost layer of longitudinal fibres; these form the detrusor muscle, which can be seen with the naked eye.<ref name=Wheaters2013 />

The outside of the bladder is protected by a [[serous membrane]] called [[adventitia]].<ref name=Wheaters2013/><ref name=Fry2016rev>{{cite journal|last1= Fry|first1= CH|last2= Vahabi|first2= B|title= The Role of the Mucosa in Normal and Abnormal Bladder Function.|journal= Basic & Clinical Pharmacology & Toxicology|date= October 2016|volume= 119|issue= Suppl 3|pages= 57–62|doi= 10.1111/bcpt.12626|pmid= 27228303|pmc=5555362}}</ref>

<gallery>
File:Gray1141.png|Vertical section of bladder wall
File:Urinary bladder.JPG|Layers of the bladder wall and cross-section of the detrusor muscle
File:2605 The Bladder.jpg|Anatomy of the male bladder, showing transitional epithelium and part of the wall in a histological cut-out
</gallery>

===Development===
{{Further|Development of the urinary system}}
In the developing [[embryo]], at the hind end lies a [[Cloaca (embryology)|cloaca]]. This, over the fourth to the seventh week, divides into a [[urogenital sinus]] and the beginnings of the [[anal canal]], with a wall forming between these two inpouchings called the [[urorectal septum]].<ref name=Langman2019>{{cite book |last1=Sadley |first1=TW |title=Langman's medical embryology |date=2019|location=Philadelphia|publisher=Wolters Kluwer |isbn=9781496383907 |edition=14th|section=Bladder and urethra|pages=263–66}}</ref> The urogenital sinus divides into three parts, with the upper and largest part becoming the bladder; the middle part becoming the [[urethra]], and the lower part changes depending on the biological sex of the embryo.<ref name=Langman2019 />

The human bladder derives from the [[urogenital sinus]], and it is initially continuous with the [[allantois]]. The upper and lower parts of the bladder develop separately and join around the middle part of [[prenatal development|development]].<ref name="Viana"/> At this time the ureters move from the [[mesonephric duct]]s to the trigone.<ref name="Viana"/> In males, the base of the bladder lies between the rectum and the pubic symphysis. It is superior to the [[prostate]], and separated from the [[rectum]] by the [[recto-vesical pouch]]. In females, the bladder sits inferior to the uterus and anterior to the vagina; thus its maximum capacity is lower than in males. It is separated from the [[uterus]] by the [[vesico-uterine pouch]]. In [[infants]] and young children the urinary bladder is in the [[abdomen]] even when empty.<ref>{{cite book |author1= Moore, Keith L. |author2= Dalley, Arthur F |title= Clinically Oriented Anatomy|url= https://archive.org/details/clinicallyorient00moor_1 |url-access= registration |edition= 5th |year= 2006 |publisher= Lippincott Williams & Wilkins |isbn= 9780781736398 }}</ref>

==Function==
{{Main|Urination}}[[File:Bladder.jpg|thumb|Female urinary bladder]][[Urine]] is excreted by the [[kidney]]s and flows into the bladder through the [[ureter]]s, where it is stored until [[urination]] (micturition).<ref name="Ganong2019">{{Cite book|title=Ganong's review of medical physiology| first1 = Kim E | last1 = Barrett | first2 = Susan M | last2 = Barman | first3 = Jason X-J | last3 = Yuan | first4 = Heddwen | last4 = Brooks |isbn=9781260122404 |edition=26th |location=New York |oclc=1076268769 |year=2019|chapter=37. Renal function & Micturition: The Bladder|pages=681–682}}</ref> Urination involves coordinated muscle changes involving a reflex based in the spine, with higher inputs from the brain.<ref name="Ganong2019" /> During urination, the detrusor muscle contracts, the external urinary sphincter and muscles of the [[perineum]] relax, and urine flows through the [[urethra]]<ref name="Ganong2019" /> and exits the [[penis]] or [[vulva]] through the [[urinary meatus]].<ref name="Grays2016">{{Cite book|url=https://www.worldcat.org/oclc/920806541|title=Gray's anatomy : the anatomical basis of clinical practice|year=2016|isbn=9780702052309|editor=Standring, Susan|edition=41st|location=Philadelphia|pages=1255–1261|section=Urinary bladder|oclc=920806541}}</ref>

The urge to pass urine stems from [[stretch receptor]]s that activate when between 300 - 400 mL urine is held within the bladder.<ref name="Ganong2019" /> As urine accumulates, the [[rugae]] flatten and the wall of the bladder thins as it stretches, allowing the bladder to store larger amounts of urine without a significant rise in internal pressure.<ref>{{cite book |author=Marieb, Mallatt |title=Human Anatomy |edition=5th |publisher=Pearson International |chapter=23 |page=700}}</ref> Urination is controlled by the [[pontine micturition center]] in the [[brainstem]].<ref name="Purves">{{cite book|last1=Purves|first1=Dale|title=Neuroscience|date=2011|publisher=Sinauer|location=Sunderland, Mass.|isbn=978-0-87893-695-3|page=471|edition=5.}}</ref>

[[Stretch receptor]]s in the bladder signal the [[parasympathetic]] nervous system to stimulate the [[muscarinic receptor]]s in the detrusor to contract the muscle when the bladder is distended.<ref name="Giglio">{{cite journal|last1= Giglio|first1= D|last2= Tobin|first2= G|title=Muscarinic receptor subtypes in the lower urinary tract |journal= Pharmacology|date= 2009|volume= 83|issue= 5|pages= 259–69|pmid= 19295256|doi=10.1159/000209255|doi-access= free}}</ref> This encourages the bladder to expel urine through the urethra. The main receptor activated is the [[Muscarinic acetylcholine receptor M3|M3 receptor]], although [[Muscarinic acetylcholine receptor M2|M2 receptors]] are also involved and whilst outnumbering the M3 receptors they are not so responsive.<ref name="Uchiyama">{{cite journal|last1= Uchiyama|first1= T|last2= Chess-Williams|first2= R|title= Muscarinic receptor subtypes of the bladder and gastrointestinal tract |journal= Journal of Smooth Muscle Research = Nihon Heikatsukin Gakkai Kikanshi|date= December 2004|volume= 40|issue= 6|pages= 237–47|pmid= 15725706|doi=10.1540/jsmr.40.237|doi-access= free}}</ref>

The main relaxant pathway is via the [[adenylyl cyclase]] [[Cyclic adenosine monophosphate|cAMP]] pathway, activated via the β3 adrenergic receptors. The [[Beta-2 adrenergic receptor|β2 adrenergic receptors]] are also present in the detrusor and even outnumber β3 receptors, but they do not have as important an effect in relaxing the detrusor smooth muscle.<ref name="Andersson" /><ref>{{Cite journal|last1=Moro|first1=Christian|last2=Tajouri|first2=Lotti|last3=Chess-Williams|first3=Russ|title=Adrenoceptor Function and Expression in Bladder Urothelium and Lamina Propria|journal=Urology|volume=81|issue=1|pages=211.e1–211.e7|doi=10.1016/j.urology.2012.09.011|pmid=23200975|year=2013}}</ref><ref name=":0">{{Cite journal|title=Neurophysiology of Stress Urinary Incontinence|journal=Rev. Urol.|volume=6|pages=S19–28|pmid=16985861|pmc=1472861|year=2004|last1=Chancellor|first1=M. B.|last2=Yoshimura|first2=N.|issue=Suppl 3 }}</ref>

==Clinical significance==
{{See also|Urinary bladder disease}}

===Inflammation and infection===
[[File:Schistosomiaisis Bladder Calcifications.png|thumb|right|260px|Calcifications on bladder wall caused by urinary [[schistosomiasis]]]]
[[Cystitis]] refers to infection or inflammation of the bladder. It commonly occurs as part of a [[urinary tract infection]].{{sfn|Davidson's|2018|pp=426-429}} In adults, it is more common in women than men, owing to a shorter [[urethra]]. It is common in males during childhood, and in older men where [[benign prostatic hypertrophy|an enlarged prostate]] may cause urinary retention.{{sfn|Davidson's|2018|pp=426-429}} Other risk factors include other causes of blockage or narrowing, such as [[prostate cancer]] or the presence of [[vesico-ureteric reflux]]; the presence of outside structures in the urinary tract, such as [[urinary catheter]]s; and neurologic problems that make passing urine difficult.{{sfn|Davidson's|2018|pp=426-429}} Infections that involve the bladder can cause pain in the lower abdomen (above the [[pubic symphysis]], so called "suprapubic" pain), particularly before and after passing urine, and a desire to [[urinary frequency|pass urine frequently]] and with little warning ([[urinary urgency]]).{{sfn|Davidson's|2018|pp=426-429}} Infections are usually due to [[bacteria]], of which the most common is [[E coli]].{{sfn|Davidson's|2018|pp=426-429}}

When a urinary tract infection or cystitis is suspected, a [[medical practitioner]] may request a [[urine sample]]. A [[urine dipstick|dipstick placed in the urine]] may be used to see if the urine has [[leukocytes|white blood cells]], or the presence of [[nitrates]] which may indicate an infection. The urine specimen may be also sent for [[microbial culture and sensitivity]] to assess if a particular bacteria grows in the urine, and identify its [[antibiotic sensitivities]].{{sfn|Davidson's|2018|pp=426-429}} Sometimes, additional investigations may be requested. These might include testing the function of the kidneys by assessing [[electrolytes]] and [[creatinine]]; investigating for blockages or narrowing of the renal tract with an [[renal tract ultrasound|ultrasound]], and testing for an enlarged prostate with a [[digital rectal examination]].{{sfn|Davidson's|2018|pp=426-429}}

Urinary tract infections or cystitis are treated with [[antibiotic]]s, many of which are [[per oral|consumed by mouth]]. Serious infections may require treatment with [[intravenous]] antibiotics.{{sfn|Davidson's|2018|pp=426-429}}

[[Interstitial cystitis]] refers to a condition in which the bladder is infected due to a cause that is not bacteria.<ref>{{cite web | title = Interstitial cystitis | publisher = Mayo Clinic | date = 14 September 2019 | url = https://www.mayoclinic.org/diseases-conditions/interstitial-cystitis/symptoms-causes/syc-20354357 | access-date = 10 May 2020}}</ref><ref>{{cite book |last1=Glass |first1=Cheryl A. |last2=Gunter |first2=Debbie |editor1-last=Glass |editor1-first=Cheryl A. |editor2-last=Cash |editor2-first=Jill C. |title=Family Practice Guidelines |date=2017 |publisher=pringer Publishing Company, LLC |location=New York |isbn=978-0826177117 |pages=352–353 |edition=4}}</ref>

===Incontinence and retention===
[[File:UltrasoundBPH.jpg|thumb|Urinary bladder (black butterfly-like shape) and hyperplastic [[prostate]] (BPH) visualized by [[medical ultrasound]]]]Frequent urination can be due to excessive urine production, small bladder capacity, irritability or incomplete emptying. Males with an [[enlarged prostate]] urinate more frequently. One definition of an [[overactive bladder]] is when a person urinates more than eight times per day.<ref>{{cite web|url=https://www.cornellurology.com/clinical-conditions/female-urology-urogynecology/overactive-bladder|title=Overactive Bladder|publisher=Cornell Medical College|access-date=2013-08-21|archive-date=2 June 2016|archive-url=https://web.archive.org/web/20160602223527/https://www.cornellurology.com/clinical-conditions/female-urology-urogynecology/overactive-bladder/|url-status=dead}}</ref> An overactive bladder can often cause [[urinary incontinence]]. Though both urinary frequency and volumes have been shown to have a circadian rhythm, meaning day and night cycles,<ref>{{cite journal|last=Negoro|first=Hiromitsu|title=Involvement of urinary bladder Connexin43 and the circadian clock in coordination of diurnal micturition rhythm|year=2012|doi=10.1038/ncomms1812|pmid=22549838|pmc=3541943|volume=3|journal=Nature Communications|page=809|bibcode=2012NatCo...3..809N}}</ref> it is not entirely clear how these are disturbed in the overactive bladder. [[Urodynamic testing]] can help to explain the symptoms. An [[underactive bladder]] is the condition where there is a difficulty in passing urine and is the main symptom of a [[neurogenic bladder]]. Frequent urination at night may indicate the presence of [[bladder stone]]s.

Disorders of or related to the bladder include:
* [[bladder exstrophy]]
* [[bladder sphincter dyssynergia]], a condition in which the sufferer cannot coordinate relaxation of the urethra sphincter with the contraction of the bladder muscles
* [[paruresis]]
* [[trigonitis]]
* [[underactive bladder]], a condition with its main symptom being [[urinary retention]].<ref>{{Cite journal|last1=C|first1=Moro|last2=C|first2=Phelps|last3=V|first3=Veer|last4=J|first4=Clark|last5=P|first5=Glasziou|last6=Kao|first6=Tikkinen|last7=Am|first7=Scott|date=2021-11-24|title=The effectiveness of parasympathomimetics for treating underactive bladder: A systematic review and meta-analysis|url=https://pubmed.ncbi.nlm.nih.gov/34816481/|journal=Neurourology and Urodynamics|volume=41 |issue=1 |pages=127–139 |language=en|doi=10.1002/nau.24839|issn=1520-6777|pmid=34816481|s2cid=244530010 }}</ref>

Disorders of bladder function may be dealt with surgically, by redirecting the flow of urine or by replacement with an [[artificial urinary bladder]]. The volume of the bladder may be increased by [[bladder augmentation]]. [[Urinary bladder neck obstruction|An obstruction of the bladder neck]] may be severe enough to warrant surgery. [[Ultrasound]] can be used to estimate bladder volumes.<ref>{{Cite journal |last1=Bih |first1=L. I. |last2=Ho |first2=C. C. |last3=Tsai |first3=S. J. |last4=Lai |first4=Y. C. |last5=Chow |first5=W. |date=December 1998 |title=Bladder shape impact on the accuracy of ultrasonic estimation of bladder volume |url=https://pubmed.ncbi.nlm.nih.gov/9862299/ |journal=Archives of Physical Medicine and Rehabilitation |volume=79 |issue=12 |pages=1553–1556 |doi=10.1016/s0003-9993(98)90419-1 |issn=0003-9993 |pmid=9862299}}</ref><ref>{{Cite web |title=Bladder Volume Calculator |url=https://radathand.com/radiology-calculators/body-imaging/bladder-volume-calculator/ |access-date=2024-07-11 |website=Rad At Hand |date=10 July 2024 |language=en-US}}</ref>

===Cancer===
{{main|Bladder cancer}}

[[File:Bladder Cancer.jpg|thumb|231x231px|Cross-section of the male [[genitourinary system]] showing a cancer within the bladder. When a cancer occurs it is most likely to be a [[transitional cell carcinoma]].]]
[[Cancer]] of the bladder is known as [[bladder cancer]]. It is usually due to cancer of the [[urothelium]], the cells that line the surface of the bladder. Bladder cancer is more common after the age of 40, and more common in men than women;<ref name="Davidsons2018cancer">{{cite book|title=Davidson's principles and practice of medicine|editor1-last=Ralston |editor1-first=Stuart H. |editor2-last=Penman |editor2-first=Ian D. |editor3-last=Strachan |editor3-first=Mark W. |editor4-last=Hobson |editor4-first=Richard P. |date=2018 |publisher=Elsevier |isbn=978-0-7020-7028-0 |edition=23rd|pages=435–6|section=Urothelial tumours}}</ref> other risk factors include [[smoking]] and exposure to [[dye]]s such as [[aromatic amine]]s and [[aldehydes]].<ref name="Davidsons2018cancer" /> When cancer is present, the most common symptom in an affected person is [[haematuria|blood in the urine]]; a physical [[medical examination]] may be otherwise normal, except in late disease.<ref name="Davidsons2018cancer" /> Bladder cancer is most often due to cancer of the cells lining the ureter, called [[transitional cell carcinoma]], although it can more rarely occur as a [[squamous cell carcinoma]] if the type of cells lining the urethra have changed due to chronic inflammation, such as due to stones or [[schistosomiasis]].<ref name="Davidsons2018cancer" />

Investigations performed usually include collecting a sample of urine for an inspection for malignant cells under a microscope, called [[cytology]], as well as [[medical imaging]] by a [[CT urogram]] or [[ultrasound]].<ref name="Davidsons2018cancer" /> If a concerning lesion is seen, a flexible camera may be inserted into the bladder, called [[cystoscopy]], in order to view the lesion and take a [[biopsy]], and a [[CT scan]] will be performed of other body parts (a [[Full-body CT scan|CT scan of the chest, abdomen and pelvis]]) to look for additional {{wt|en|metastatic}} lesions.<ref name="Davidsons2018cancer" />

Treatment depends on the cancer's [[tumour staging|stage]]. Cancer present only in the bladder may be removed surgically via [[cystoscopy]]; an injection of the [[chemotherapy|chemotherapeutic]] [[mitomycin C]] may be performed at the same time.<ref name="Davidsons2018cancer" /> Cancers that are [[tumour grade|high grade]] may be treated with an injection of the [[BCG vaccine]] into the bladder wall, and may require surgical removal if it does not resolve.<ref name="Davidsons2018cancer" /> Cancer that is invading through the bladder wall may be managed by complete surgical removal of the bladder ([[radical cystectomy]]), with the ureters diverted into a segment of part of [[ileum]] connected to a [[stoma bag]] on the skin.<ref name="Davidsons2018cancer" /> Prognosis can vary markedly depending on the cancer's stage and grade, with a better prognosis associated with tumours found only in the bladder, that are low grade, that do not invade through the bladder wall, and that is {{wt|en|papillary}} in visual appearance.<ref name="Davidsons2018cancer" />

===Investigation===
[[File:Bladderdiverticulum.png|thumb|A [[diverticulum]] of the bladder]]A number of investigations are used to examine the bladder. The investigations that are ordered will depend on the taking of a [[medical history]] and an examination. The examination may involve a [[medical practitioner]] feeling in the suprapubic area for tenderness or fullness that might indicate an inflamed or full bladder.{{citation needed|date=July 2020}} Blood tests may be ordered that may indicate inflammation; for example a [[full blood count]] may demonstrate elevated [[white blood cell]]s, or a [[C-reactive protein]] may be elevated in an infection.{{citation needed|date=July 2020}}

Some forms of [[medical imaging]] exist to visualise the bladder. A [[bladder ultrasound]] may be conducted to view how much urine is within the bladder, indicating [[urinary retention]]. A [[urinary tract ultrasound]], conducted by a more trained operator, may be conducted to view whether there are stones, tumours or sites of obstruction within the bladder and urinary tract. A [[Computed tomography of the abdomen and pelvis|CT scan]] may also be ordered.

A flexible internal camera, called a [[cystoscope]], can be inserted to view the internal appearance of the bladder and take a [[biopsy]] if required.

[[Urodynamic testing]] can help to explain the symptoms.

==Other animals==
=== Mammals ===
{{Multiple image
| image1            = The anatomy of the domestic animals (1914) (20553749470).jpg
| image2            = The anatomy of the domestic animals (1914) (18009226539).jpg
| footer            = Bladder, prostate, and seminal vesicles of a [[stallion]]
| width             = 220
| total_width       = 220
}}
All species of mammal have a urinary bladder.<ref>{{Cite book |last1=Flower |first1=William Henry |url=https://books.google.com/books?id=YclRAAAAMAAJ&dq=bladder&pg=PA69 |title=An Introduction to the Study of Mammals Living and Extinct |last2=Lydekker |first2=Richard |date=1891 |publisher=A. and C. Black |language=en}}</ref> This structure begins as an [[embryonic cloaca]]. In the vast majority of species, it eventually becomes differentiated into a dorsal part, connected to the intestine, and a ventral part, associated with the urinogenital passage and urinary bladder. The only mammals in which this does not take place are the [[platypus]] and the [[Echidna|spiny anteater]], both of which retain the cloaca into adulthood.<ref name="ABC">{{cite book|url=https://archive.org/stream/chordates00rand/#page/276/mode/1up/search/bladder|title=The Chordates|date=1950|publisher=Balkiston|author=Herbert W. Rand}}</ref>

The mammalian bladder is an organ that regularly stores a hyperosmotic concentration of urine. It therefore is relatively impermeable and has a multi-layer epithelium. The urinary bladders of [[cetacean]]s (whales and dolphins) are proportionally smaller than those of land-dwelling mammals.<ref name="Hunter2015">{{cite book|url=https://books.google.com/books?id=TNAIBwAAQBAJ&pg=PR35|title=The Works of John Hunter, F.R.S.|date=26 March 2015|publisher=Cambridge University|isbn=978-1-108-07960-0|page=35|author=John Hunter}}</ref>

=== Reptiles ===
In all reptiles, the urinogenital ducts and the [[rectum]] both empty into the organ called the [[cloaca]]. In some reptiles, a midventral wall in the cloaca opens into a urinary bladder. The urinary bladder exists in all species of turtle and tortoise and most species of lizard. [[Monitor lizard]]s, the [[legless lizard]]s, snakes, alligators, and crocodiles do not have urinary bladders.<ref name="ABC" />{{rp|p. 474}}

Many turtles, tortoises, and lizards have proportionally very large bladders. [[Charles Darwin]] noted that the bladder of the [[Galapagos tortoise]] could store urine weighing up to 20% of the tortoise's body weight.<ref name="Bentley2013" /> Such adaptations are the result of environments, such as remote islands and deserts, where fresh water is very scarce.<ref>{{Cite journal|last=Paré|first=Jean|date=January 11, 2006|title=Reptile Basics: Clinical Anatomy 101|url=http://www.ivis.org/proceedings/navc/2006/SAE/600.pdf?LA=1|journal=Proceedings of the North American Veterinary Conference|volume=20|pages=1657–1660}}</ref> Other desert-dwelling reptiles have large bladders, which can hold long-term reserves of water for several months and aid in [[osmoregulation]].<ref>{{Cite journal|last1=Davis|first1=Jon R.|last2=DeNardo|first2=Dale F.|date=2007-04-15|title=The urinary bladder as a physiological reservoir that moderates dehydration in a large desert lizard, the Gila monster Heloderma suspectum|journal=Journal of Experimental Biology|language=en|volume=210|issue=8|pages=1472–1480|doi=10.1242/jeb.003061|issn=0022-0949|pmid=17401130|doi-access=free|bibcode=2007JExpB.210.1472D }}</ref>

Turtles have two or more accessory urinary bladders, beside the neck of the urinary bladder and above the pubis, occupying much of the body cavity.<ref>{{Cite journal|last1=Wyneken|first1=Jeanette|last2=Witherington|first2=Dawn|date=February 2015|title=Urogenital System|url=http://www.ivis.org/advances/wyneken/16.pdf?LA|journal=Anatomy of Sea Turtles|volume=1|pages=153–165}}</ref> Turtles' bladder is also usually divided into two lobes: the right lobe is under the liver, which prevents large stones from remaining in the lobe; the left lobe is likelier than the right to have [[Bladder stone (animal)|calculi]].<ref>{{Cite book|title=Reptile Medicine and Surgery|last1=Divers|first1=Stephen J.|last2=Mader|first2=Douglas R.|publisher=Elsevier Health Sciences|year=2005|isbn=9781416064770|location=Amsterdam|pages=481, 597}}</ref>

=== Amphibians ===
Most aquatic and semi-aquatic amphibians can absorb water directly through their skin. Some semi-aquatic animals also have similarly permeable bladder membranes.<ref>{{Cite journal|last1=Urakabe|first1=Shigeharu|last2=Shirai|first2=Dairoku|last3=Yuasa|first3=Shigekazu|last4=Kimura|first4=Genjiro|last5=Orita|first5=Yoshimasa|last6=Abe|first6=Hiroshi|title=Comparative study of the effects of different diuretics on the permeability properties of the toad bladder|journal=Comparative Biochemistry and Physiology Part C: Comparative Pharmacology|language=en|volume=53|issue=2|pages=115–119|doi=10.1016/0306-4492(76)90063-0|pmid=5237|year=1976}}</ref> They tend to have high rates of urine production, to offset this high water intake; and the dissolved salts in their urine are highly dilute. The urinary bladder helps these animals to retain salts. Some aquatic amphibians, such as ''[[Xenopus]]'', do not reabsorb water from their urine, to prevent excessive water influx.<ref>{{Cite journal|last1=Shibata|first1=Yuki|last2=Katayama|first2=Izumi|last3=Nakakura|first3=Takashi|last4=Ogushi|first4=Yuji|last5=Okada|first5=Reiko|last6=Tanaka|first6=Shigeyasu|last7=Suzuki|first7=Masakazu|title=Molecular and cellular characterization of urinary bladder-type aquaporin in Xenopus laevis|journal=General and Comparative Endocrinology|volume=222|pages=11–19|doi=10.1016/j.ygcen.2014.09.001|pmid=25220852|year=2015}}</ref> For land-dwelling amphibians, dehydration results in reduced urine output.<ref name="VittCaldwell2013">{{cite book|url=https://books.google.com/books?id=Gay9N_ry79kC&pg=PA184|title=Herpetology: An Introductory Biology of Amphibians and Reptiles|date=25 March 2013|publisher=Academic|isbn=978-0-12-386920-3|author1=Laurie J. Vitt|author2=Janalee P. Caldwell|page=184}}</ref>

The amphibian bladder is usually highly distensible; among some land-dwelling species of frogs and salamanders, it may account for 20%–50% of total body weight.<ref name="VittCaldwell2013" /> Urine flows from the kidneys through the ureters into the bladder and is periodically released from the bladder to the cloaca.<ref>{{Cite book |last1=Feder |first1=Martin E. |url=https://books.google.com/books?id=oaS-OpEjPtUC&pg=PA108 |title=Environmental Physiology of the Amphibians |last2=Burggren |first2=Warren W. |date=1992-10-15 |publisher=University of Chicago Press |isbn=978-0-226-23944-6 |language=en}}</ref>

=== Fish ===
The gills of most [[teleost]] fish help to eliminate ammonia from the body, and fish live surrounded by water, but most still have a distinct bladder for storing waste fluid. The urinary bladder of [[teleost]]s is permeable to water, though this is less true for freshwater dwelling species than saltwater species.<ref name="Bentley2013">{{cite book|url=https://books.google.com/books?id=U0D3BwAAQBAJ&pg=PA143|title=Endocrines and Osmoregulation: A Comparative Account in Vertebrates|date=14 March 2013|publisher=Springer Science & Business Media|isbn=978-3-662-05014-9|author=P.J. Bentley}}</ref>{{rp|p. 219}} In freshwater fish the bladder is a key site of absorption for many major ions<ref name=":2">{{Cite journal |last1=Takvam |first1=Marius |last2=Wood |first2=Chris M. |last3=Kryvi |first3=H. |last4=Nilsen |first4=Tom O. |date=2023-06-29 |title=Role of the kidneys in acid-base regulation and ammonia excretion in freshwater and seawater fish: implications for nephrocalcinosis |journal=Frontiers in Physiology |volume=14 |doi=10.3389/fphys.2023.1226068 |doi-access=free |issn=1664-042X |pmc=10339814 |pmid=37457024}}</ref> in marine fish urine is held in the bladder for extended periods to maximise water absorption.<ref name=":2" /> The urinary bladders of fish and [[tetrapod]]s are thought to be analogous while the former's swim-bladders and latter's [[lung]]s are considered homologous.

Most fish also have an organ called a [[swim-bladder]] which is unrelated to the urinary bladder except in its membranous nature. The [[loach]]es, [[pilchard]]s, and [[herring]]s are among the few types of fish in which a urinary bladder is poorly developed. It is largest in those fish which lack an air bladder, and is situated in front of the [[oviduct]]s and behind the [[rectum]].<ref>{{Cite book|title=Lectures on the comparative anatomy and physiology of the invertebrate animals|last=Owen|first=Richard|publisher=Longman, Brown, Green, and Longmans|year=1843|location=London|pages=283–284|url=https://books.google.com/books?id=pNpPpKj4_tgC}}</ref> 

=== Birds ===
{{further|Urogenital systems of birds}}
In nearly all bird species, there is no urinary bladder per se.<ref name="Ornithology2016">{{cite book|author=Cornell University. Laboratory of Ornithology|title=Handbook of Bird Biology|url=https://books.google.com/books?id=OGyQDAAAQBAJ&q=bird+urinary+bladder|date=19 September 2016|publisher=John Wiley & Sons|isbn=978-1-118-29105-4}}</ref> Although all birds have kidneys, the [[ureters]] open directly into a [[cloaca]] which serves as a reservoir for urine, fecal matter, and eggs.<ref name="Knight1854">{{cite book|url=https://archive.org/details/in.ernet.dli.2015.45180|title=The English Cyclopaedia: A New Dictionary of Universal Knowledge|publisher=Bradbury and Evans|year=1854|page=[https://archive.org/details/in.ernet.dli.2015.45180/page/n71 136]|author=Charles Knight}}</ref>

=== Crustaceans ===
Unlike the urinary bladder of vertebrates, the urinary bladder of [[crustacean]]s both stores and modifies urine.<ref name=":1">{{Cite book|url=https://books.google.com/books?id=trazj_5gCSQC&pg=PA47|title=Nonmammalian animal models for biomedical research|date=1989|publisher=CRC Press|others=Woodhead, Avril D.|isbn=0-8493-4763-7|location=Boca Raton, Fla.|pages=51–52|oclc=18816053}}</ref> The bladder consists of two sets of lateral and central lobes. The central lobes sit near the digestive organs and the lateral lobes extend along the front and sides of the crustacean's body cavity.<ref name=":1" /> The tissue of the bladder is thin [[epithelium]].<ref name=":1" />

==See also==
* [[Alpha blocker]]
* [[Cystitis glandularis]]
* [[UPK1B]]

==References==
{{Reflist}}

;Books
* {{cite book|veditors = Standring S |title=Gray's anatomy : the anatomical basis of clinical practice|date=2008|publisher=Churchill Livingstone|location=London|isbn=978-0-8089-2371-8|edition=40th|ref={{harvid|Gray's Anatomy|2008}}}}
* {{cite book|title=Davidson's principles and practice of medicine|editor1-last=Ralston |editor1-first=Stuart H. |editor2-last=Penman |editor2-first=Ian D. |editor3-last=Strachan |editor3-first=Mark W. |editor4-last=Hobson |editor4-first=Richard P. |date=2018 |publisher=Elsevier |isbn=978-0-7020-7028-0 |edition=23rd|ref={{harvid|Davidson's|2018}}}}

==External links==
{{Commons category}}
{{wiktionary}}
* {{UCDavisOrganology|Urinary/mammal/bladder/bladder1}}&nbsp;– "Mammal, bladder (LM, Medium)"
* [http://www.bladderj.org Bladder]{{Dead link|date=February 2025 |bot=InternetArchiveBot |fix-attempted=yes }} ({{ISSN|2327-2120}}) – An open-access journal on bladder biology and diseases.

{{Human systems and organs}}
{{Urinary system anatomy}}

{{Authority control}}
{{Use dmy dates|date=April 2017}}

[[Category:Urinary bladder| ]]
[[Category:Pelvis]]
[[Category:Organs (anatomy)]]
[[Category:Urinary system]]