bladder
The urinary bladder ( Latin Vesica urinaria , Greek κύστις kýstis , hence technical terms on cyst ) is an organ in animals and humans in which the urine is temporarily stored as part of the urinary tract . It enables urine to be released voluntarily and only from time to time, although urine is continuously flowing out of the kidney . In humans, the muscular hollow organ lined with urothelium is relatively well protected in the small pelvis .
The urine passes in the vertebrates from the kidneys through the ureters ( ureter ) in the urinary bladder. When emptying, the sphincter muscles on the base of the bladder are relaxed, so that the urine flows out via the urethra ( urethra ).
Men have a strong urge to urinate with a volume of around 350–750 ml, and women with 250–550 ml. Depending on external and internal stimuli, even with significantly less filling there may be an urge to urinate or involuntary emptying. The maximum capacity of the urinary bladder ( bladder capacity ) in adults is between 900 and 1500 ml, depending on body size.
Mammals
anatomy
The urinary bladder is a hollow organ that rests on the pelvic floor in humans . It is located directly behind the pubic symphysis , in front of the vagina in women and the rectum in men, although it is slightly more caudal (lower) in women . The urinary bladder extends upwards to the top of the pelvis . As the filling increases, it can reach the navel.
Its front is called the apex , the space between the pubic bone and the front wall of the bladder ( Spatium retropubicum ) "Cavum Retzii"; the posteroinferior (lower posterior) side of the fundus . The bladder neck ( cervix vesicae ) is located on the underside in primates (and thus also in humans), in other animals on the back and leads to the urethra .
The urinary bladder receives the paired ureters ( ureters ) from the two kidneys on its rear lower side . The ureters run over a short distance within the bladder wall, so that they kink when the bladder is filled to a greater extent, thus preventing backflow (physiologically in general). In addition, the contraction of the smooth muscles in the bladder wall compresses the ureters when you urinate. This also counteracts the backflow of urine.
The trigonum vesicae is the triangular surface that is formed by the entrances of the two ureters and the exit of the urethra. The trigonum vesicae also serves as a guide for the doctor during an endoscopic examination to find the ureter openings more quickly.
The urinary bladder has two sphincter muscles ( bladder sphincter ) at its exit , an inner and an outer one. The inner one consists of smooth muscles and is subject to the control of the autonomic nervous system, which means that it cannot be controlled voluntarily. The external urethral sphincter is a ring-shaped skeletal muscle that can be consciously controlled.
In addition to embedding the urethra in the pelvic floor, the urinary bladder is attached via three peritoneum folds ( serosa duplicates). A lateral urinary bladder ligament ( ligamentum vesicae laterale ) extends from the side wall of the bladder on both sides , and from the abdominal side the middle urinary bladder ligament ( ligamentum vesicae medianum ) extends to the inner wall of the abdominal cavity. The median (middle) band is a holdover from the urachus . In each of the lateral urinary bladder ligaments there is a rounded cord, the round urinary bladder ligament ( ligamentum teres vesicae ), which represents the remnant of the occluded umbilical artery ( arteria umbilicalis ). After leaving the small pelvis, all three ligaments run as part of the anterior parietoneum to the navel.
Blood supply
The urinary bladder is supplied with blood by the superior vesical arteries (upper bladder arteries, in animals this is the anterior cranial vesical artery ), a continuation of the umbilical artery (umbilical artery), which in turn arises from the internal iliac artery . It is also supplied by the inferior vesical artery (lower bladder artery, in animals this is the rear caudal vesical artery ), a branch of the internal iliac artery. In women, blood also reaches the urinary bladder from the vaginal artery , a branch of the uterine artery (uterine artery).
Blood drains through the plexus venosus vesicalis (bladder vein plexus ), in men also through the plexus venosus prostaticus (vein plexus of the prostate), which open into the internal iliac vein .
Innervation
The functional innervation of the urinary bladder is provided by the autonomic nervous system . This is not subject to conscious control and is therefore also called the autonomous nervous system . A distinction is made between two parts: the sympathetic nervous system , which becomes active in stressful, attack and flight situations , and the parasympathetic nervous system , which becomes active in quiet situations and serves to regenerate and build up the body's own reserves.
The sympathetic innervation is carried out by nerves from the plexus vesicalis et prostaticus , which are connected to the nervus hypogastricus . They relax the detrusor muscle and contract the internal sphincter muscle . This prevents involuntary urination.
The parasympathetic innervation occurs through nerves that originate in the sacral part of the spinal cord (S2 – S4). They cause the detrusor muscle to contract (see below) and the relaxation of the internal sphincter muscle, thus initiating urination ( micturition ).
The urethralis muscle is innervated by the perineal nerves ( perineal nerves), branches of the pudendal nerve (pubic nerve ).
Feinbau
The inner wall of the urinary bladder is lined with urothelium . This consists of four to six layers of cells that change their shape depending on how full the urinary bladder is. The innermost layer consists of large so-called cover cells (also superficial cells from Latin superficialis, superficial), which cover the layers below them like an umbrella. When the bladder is empty, they are umbrella-shaped; when the bladder is full, they flatten. They have polyploid (more than two sets of chromosomes) cell nuclei, there are also cells with two nuclei. On the ( apical ) side facing the inside of the urinary bladder , the cytoplasm of the cover cells condenses. This compression is the crusta (crust), which consists of a dense network of intermediary and actin filaments . The intermediate layer (transition layer) follows directly below . The cells of this layer are irregularly shaped and have wide intercellular gaps. The basal cells lie beneath this layer . This innermost layer is also called the mucosa .
The lamina propria , which is directly connected to the mucosa on the outside, contains both loose and tight connective tissue with collagenous and elastic fibers .
The tunica muscularis or muscle layer is attached to the lamina propria . It consists of smooth muscles , the detrusor vesicae (or detrusor for short ), which extends in all directions. Only at the neck of the bladder are three layers recognizable: an inner layer in which the smooth muscles run lengthways, a middle layer in which they run across, and an outer layer in which they in turn run lengthways. The fibers of the inner layer begin to run around the urethra behind the bladder neck . There they form the internal sphincter of the urinary bladder that cannot be controlled voluntarily .
The outside of the bladder is covered by the adventitia , a covering layer of loose connective tissue, except on the top, where it is covered by the peritoneum .
Ontogenetic development
The urinary bladder arises from the cloaca of the embryo . The cloaca, which is closed by the cloacal membrane, is the common origin of the urinary bladder and the rectum and is divided into an anterior and a posterior part in the fourth to seventh week of development by the formation of a partition ( urorectal septum ). The front part is now called the urogenital sinus and is covered by the urogenital membrane. The urogenital sinus is divided into three parts: The urinary bladder is the uppermost and largest part, the other parts later form the prostate and parts of the urethra in men and the entire urethra and external genital organs in women .
The ureters open into the urinary bladder and, as they develop, move cranially (towards the head). Since the ureters are derived from the kidney and the latter from the mesoderm (the middle cotyledon of the embryoblast ), the bladder mucous membrane that is created by including these ducts is also of mesodermal origin. This part corresponds to the urinary bladder triangle ( Trigonum vesicae ). This contrasts with the rest of the bladder, which is of entodermal origin due to its descent from the urogenital sinus . The mesodermal cells, however, are overgrown by endodermal cells, so that ultimately the entire mucous membrane of the bladder comes from the endoderm.
Various malformations are possible in the development of the urinary bladder .
In the case of a cleft bladder (technically exstrophy of the urinary bladder ), the mesoderm does not migrate between the ectoderm and the cloaca, which normally takes place in the fourth week of development. This means that no muscles or connective tissue can form on the anterior abdominal wall. The front wall of the bladder (from the endoderm) is therefore only covered with a thin layer of skin (this develops from the ectoderm ). As this wall, which consists of only two layers, dissolves, the back wall of the bladder becomes visible. This malformation occurs with a frequency of 1 in every 10,000 to 40,000 births and is slightly more than twice as common in boys as in girls. It requires surgical correction.
A Urachus persistence is an ontogenetic malformation, wherein the portion lying between the navel and bladder allantois is not completely recovered. Depending on the extent to which persisted the allantois (persists) is called Urachussinus , Urachuszyste , Urachusdivertikel and urachal fistula . In the case of urachus fistula, there is a connection between the urinary bladder and the navel so that urine can flow out of the navel. In contrast, in the Urachus sinus only a small piece of the allantois remains near the navel. This is also known as the “outer uracheal fistula” and manifests itself as a “weeping navel”. The “inner urachus fistula” or urachus diverticulum is used when only the lower part of the allantois, close to the urinary bladder, remains and is still connected to it. This manifests itself as a "pointed" drawn out bladder apex. It is possible that only a fluid-filled cavity (urachus cyst) remains of the allantois. Since abscesses can form, an uracheal cyst should be surgically removed.
physiology
The urine is produced in the kidneys, collected there in the renal pelvis and emptied through the ureters into the urinary bladder. Its wall is stretched by the increasing filling, which is perceived by expansion sensors. This triggers a reflex - the so-called micturition reflex - in parasympathetic centers of the sacral spinal cord , which triggers the contraction of the detrusor muscle in the bladder wall and relaxation of the internal sphincter muscle. The associated reflex pathways run in the pelvinus nerve. Urination only begins when the external sphincter is consciously relaxed. However, this conscious control of the external sphincter muscle can be overridden by inhibiting impulses from the pudendal nerve if the bladder is very full.
Urination is controlled by autonomic reflexes in the sacral spinal cord, which higher areas of the central nervous system influence by either inhibiting or stimulating. In the brain stem , more precisely in the pons (bridge), there are centers that inhibit and stimulate the micturition reflex ( pontine micturition center , part of the reticular formation ). There are also centers in the cerebral cortex that mainly have an inhibitory effect, but can, under certain circumstances, have a stimulating effect. The micturition reflex is the main cause of urination, but the final control is incumbent on these higher centers. They inhibit the reflex unless there is a conscious effort to urinate; they can delay urination by contraction of the external sphincter, and they can induce urination by stimulating the sacral centers.
Voluntary urination begins by contracting the abdominal muscles . This will compress the bladder and increase the pressure. This presses urine into the bladder neck and the urethra, which stimulates their strain sensors and triggers the micturition reflex. In addition, the external sphincter is inhibited. If urination is not disturbed and has not been stopped prematurely, usually no more than five to ten milliliters of urine remain in the bladder.
The first sensation of urine accumulation in the bladder occurs at around 80 ml in humans. With approx. 300 to 500 ml the need to empty the bladder is felt.
Investigation methods
The urinary bladder can be imaged using sonography , x-rays , magnetic resonance imaging , computed tomography and endoscopically.
Imaging of the first choice is the procedures without x-rays , mostly sonography.
The x-ray of the urinary bladder is called cystography . Since soft parts are in principle hardly visible on X-ray images, triiodinated contrast medium is used for filling, for example . This technique can also make bladder diverticula , tumors and non-radiopaque foreign bodies visible. The main application of a micturition cystourethrogram is the search for reflux, VUR .
In a cystoscopy (urethral and bladder endoscopy ), the urinary bladder (in men also the urethra) is viewed with the help of an endoscope and examined for tumors and other diseases.
If urine is to be collected for examination, drained because of urinary incontinence or for other reasons , a urinary catheter can be inserted . This is a plastic tube that is inserted into the bladder either through the urethra (transurethral) or the abdominal wall (suprapubic bladder fistula or abdominal wall catheter). Sometimes the urinary bladder is punctured ( cystocentesis ) with a cannula , usually under ultrasound control, to obtain sterile urine for examination.
The function of the urinary bladder is examined using urodynamics . This examination determines how the bladder and its sphincter behave when it is filled and emptied. For this purpose, a catheter is placed in the urinary bladder, through which the bladder is filled with fluid at body temperature and the pressure inside the bladder is measured. Another pressure sensor in the anus and electrodes for measuring muscle activity on the perineum are also required. If possible, the urine stream is also measured with a uroflow .
In dogs and cats, the urinary bladder can be felt through the abdominal wall , since it is already in front of the pelvis when it is moderately full.
Diseases
One of the most common diseases of the bladder is inflammation of the bladder ( cystitis ), which is an infection that ascends through the urethra and can then ascend to the kidneys. This condition is more common in women due to the shorter urethra.
An irritable bladder is a constant irritation of the bladder. It is caused, for example, by hypothermia and manifests itself as a constant need to urinate with only small amounts of urine. Is the locking mechanism on which z. B. the pelvic floor muscles are also involved, disturbed, it comes to involuntary leakage of urine ( urinary incontinence ). In bitches, a weak bladder neck and thus incontinence can occur after castration . Urinary incontinence is the inability to voluntarily control urination. This can have psychological (e.g. stress) or physiological causes (e.g. after paraplegia). In urinary incontinence, the control of the external sphincter and the inhibition of the parasympathetic innervation are temporarily or permanently lost. In the United States, there is also the popularly known teacher's bladder , a problem that particularly affects middle-aged women who work as primary school teachers or nurses and rarely go to the toilet during the day because of the way they work can go. The result is an overstretched urinary bladder, the sensors and muscle tone of which no longer function normally. The affected women can hold back the urine for a long time, but do not notice in time when the limit has been reached. The problem is serious and occasionally leads to occupational disability. If the pelvic floor is weak, the bladder can sink and bulge into the vagina ( cystocele ).
Cancer of the bladder is one of the most common types of cancer in Germany , with an incidence of 25,950 per year (2006) . In 95% of the cases it is a tumor of the bladder lining, a so-called urothelial carcinoma . Bladder cancer is characterized by a high rate of recurrence (recurrence) and a rather low rate of progression (progression). Treatment is usually carried out by a transurethral resection of the bladder tumor.
The bar bladder is a bar-like thickening of the muscles (so-called hypertrophy ). It leads to an irregular inner contour and ultimately to the reduced ability of the bladder to contract. This usually goes unnoticed, as there is no pain and only minor impairment of urination. Only through further complaints, such as residual urine , increased urinary tract infections or kidney congestion, does the problem manifest itself and requires treatment.
Bladder neck obstruction is a blockage of the bladder neck that makes it difficult to urinate. As Blasenhalsstenose the inability of the involuntary (inner) sphincter is referred to slacken. If this is innate, it is called Marion disease .
An abnormally large urinary bladder is called a megacystis .
If the spinal cord is severed above the twelfth breast segment (Th12), for example in the case of paraplegia , what is known as a reflex bubble occurs . Since there is no voluntary control of the external sphincter muscle, the regulation of urination only takes place involuntarily, in the second to fourth cross segments (S2 to S4 sections) of the spinal cord, which are below the injury. When the bladder fills and the bladder wall is stretched, reflex relaxation of the internal sphincter occurs and the bladder is partially emptied.
In the case of a rupture of the bladder (also known as a rupture of the bladder), external force causes traumatic tearing of the bladder. A distinction is made between the intraperitoneal rupture of the bladder , which occurs when the lower abdomen is subjected to force while the bladder is very full, and the extraperitoneal rupture of the bladder , which often occurs as a result of a pelvic rupture . As symptoms strong urge to urinate occurs while inability to urination.
On April 4, 2006, researchers at the Wake Forest University School of Medicine in North Carolina , USA, headed by Professor Anthony Atala, announced that they had succeeded in transplanting laboratory-grown bladders into humans. This is the first time that organs have been grown entirely in the laboratory. Since these grafts were grown from cells from the patient, there is no risk of rejection reactions .
In mammals (especially house dogs , house cats , house guinea pigs , house rabbits ), urinary stones ("bladder stones") or smaller crystal clusters ("bladder gravel") often form in the bladder , which, when there is a high content of poorly soluble compounds and shifts in the pH value (feeding errors) as well around inflammatory cells can arise. Bladder stones are rare in humans.
An idiopathic urinary bladder inflammation known as Feline Lower Urinary Tract Disease ( FLUTD ) is common in domestic cats .
Urinary bladder in non-mammals
In invertebrates with nephridia , these urine-forming organs expand in their end section to form the urinary bladder.
There are essentially two forms of vertebrate animals. In some female sharks (Neoselachia) and many real bony fish (Teleostei), the two ureters form a bladder-like fusion that acts as a "urinary bladder".
In amphibians (in certain frogs with drought adaptations as a water storage organ; see water reservoir frog ), a number of lizards , turtles , bridge lizards and ostriches , the ureters open into the cesspool . A short passage from the cloaca leads into the urinary bladder, also known as a urinary bag . There is no urinary bladder in snakes , crocodiles or any other bird.
Cultural history
Since prepared urinary bladders from slaughtered animals are stable and watertight, they served numerous purposes in the cultural history of mankind, for example as one of the first containers used for storing and transporting liquids, cheese or documents. In Europe, pig bladders, which arose during home slaughter, were mainly cleaned and used. Traditionally, some types of sausage (such as bubble sausage ) and meat dishes ( Palatinate saumag ) are made using animal bubbles as a casing.
In the Middle Ages, wooden frames covered with pig bladders were used to replace glass windows.
Dried and inflated urinary bladders were used as toys for children: Henry VIII , King of England, says that he liked to play football with a pig's bladder , while children in the country used the inflated pig bladders as early balloons. The bladders from slaughtered animals were also used in culinary terms. Vincenzo Tanara's L'Economia del Cittadino in Villa (“The Economy in the Town House”) from 1687 tells of a recipe that was used at banquets. A small pig's bladder was filled with the yolk of approx. 25 eggs, then dipped in boiling water until the yolk was firm. The resulting ball was placed in a larger bladder filled with the egg white of the eggs. This was then also immersed in boiling water until the egg white had also set. So you got a "giant egg".
Tycho Brahe is said to have suffered a ruptured urinary bladder at a banquet of the emperor , as court etiquette forbade guests to get up from the table in front of the emperor.
Bladder stones were a common condition due to diet into the 19th century . Since the Hippocratic oath forbade doctors to treat them, the profession of lithotomus (stone cutter) emerged. Its most famous representative was Johann Andreas Eisenbarth ("Doctor Eisenbarth").
The Eskimos in Alaska believed that the bladder was the seat of the soul; that is why the bladders from killed seals were collected over the year . Once a year they were artistically decorated and returned to the sea at the Bubble Festival , so that new animals were formed from them, which could then be hunted in the coming year. In addition, the Eskimos strung drums with the bladders of whales .
In the Swabian-Alemannic Carnival , inflated pig bladders ( Saubloodere ) that are waved on sticks or strings are a traditional fool's device. The Saublodere can be used to make noise, but they are also used to beat passers-by or other fools.
literature
- Nadja Mobjerg: organs of osmoregulation and excretion. In: W. Westheide, R. Rieger: Special Zoology. Part 2: vertebrates or skulls. Spektrum, Munich 2004, ISBN 3-8274-0307-3 .
- Frank H. Netter, Eckehard Renner: color atlases of medicine. Volume 2. Kidney and Urinary Tract. Thieme, Stuttgart 1983, ISBN 3-13-524102-5 .
- Uwe Gille: urinary and sexual system, urogenital apparatus. In: Salomon, Geyer, Gille (ed.): Anatomy for veterinary medicine. Enke-Verlag, Stuttgart 2004, ISBN 3-8304-1007-7 .
Web links
Individual evidence
- ↑ Urodynamics (urinary bladder pressure measurement): cystometry. urologielehrbuch.de; Retrieved January 11, 2010.
- ↑ P. Reuter: The Great Reuter. Springer universal dictionary of medicine, pharmacology and dentistry. Springer, Berlin 2005, ISBN 3-540-25104-9 , p. 234.
- ↑ Working Group of Scientific Medical Societies : Guidelines of the German Society for Pediatric Surgery AWMF ( Memento of March 30, 2008 in the Internet Archive )
- ↑ Human embryology script from the Universities of Friborg, Lausanne and Bern.
- ↑ Eroding the quality of life ( Memento of the original from December 14, 2011 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ; Kerri Durnell Schuiling, Frances E. Likis: Women's gynecologic health. Jones and Bartlett, 2006, ISBN 0-7637-4717-3 , p. 643; Prevalence of lower urinary tract symptoms among female elementary school teachers in Taipei .
- ^ Cancer in Germany. ( Memento of September 29, 2007 in the Internet Archive ) (PDF) 5th edition. Robert Koch Institute , Saarbrücken 2006, ISBN 3-9808880-3-7
- ↑ A. Atala, SB Bauer, S. Soker, JJ Yoo, AB Retik: Tissue-engineered autologous bladders for patients needing cystoplasty. in: The Lancet . Elsevier, London 2006 (April 15). PMID 16631879 ISSN 0023-7507
- ↑ Regionalgeschichte.net ( Memento of the original from March 18, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Football history: Kicking at court . ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. Star.
- ↑ From the pig's bladder to the rubber twist. ( Memento of August 7, 2007 in the Internet Archive ) In: Gezetera. Germanist newspaper. German seminar at the University of Basel.
- ↑ Italian cuisine. Cooking recipes from Veneto (Veneto). ( Memento from July 14, 2011 in the Internet Archive )
- ↑ Hans Himmelträger : Eskimo artist. Strecker & Schröder, Stuttgart 1938; Röth, Eisenach 1953.
- ↑ Narrenspiegel ( Memento from January 23, 2009 in the Internet Archive )
