The urinary bladder, or simply bladder, is a
hollow organ
In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a ...
in
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
s and other
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s that stores
urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
from the
kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
s before disposal by
urination. In humans the bladder is a distensible organ that sits on the
pelvic floor
The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus muscle, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the lev ...
. Urine enters the bladder via the
ureters and exits via the
urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
. The typical adult human bladder will hold between 300 and (10.14 and ) before the urge to empty occurs, but can hold considerably more.
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 vesical veins are veins in the pelvis that drain blood from the urinary bladder. The vesical veins receive blood from the vesical venous plexus
The vesical plexus envelops the lower part of the bladder and the base of the prostate
The ...
. The modern Latin word for "bladder" – ''cystis'' – appears in associated terms such as
cystitis (inflammation of the bladder).
Structure
![Male and female bladder](https://upload.wikimedia.org/wikipedia/commons/6/64/Male_and_female_bladder.svg)
In humans, the bladder is a hollow muscular organ situated at the base of the
pelvis
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The ...
. In
gross anatomy
Gross anatomy is the study of anatomy at the visible or macroscopic level. The counterpart to gross anatomy is the field of histology, which studies microscopic anatomy. Gross anatomy of the human body or other animals seeks to understand the rel ...
, the bladder can be divided into a broad , a body, an apex, and a neck.
The apex (also called the vertex) is directed forward toward the upper part of the
pubic symphysis, and from there the
median umbilical ligament
In human anatomy, the median umbilical ligament is an unpaired midline ligamentous structure upon the lower inner surface of the anterior abdominal wall. It is covered by the median umbilical fold.
The median umbilical ligament represents the re ...
continues upward on the back of the anterior abdominal wall to the
umbilicus. The
peritoneum
The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...
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 that surrounds the
internal urethral orifice
The internal urethral orifice is the opening of the urinary bladder into the urethra. It is placed at the apex of the trigonum vesicae, in the most dependent part of the bladder, and is usually somewhat crescent-shaped; the mucous membrane immedi ...
that leads to the urethra.
In males the neck of the urinary bladder is next to the
prostate gland
The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and physio ...
.
The bladder has three openings. The two
ureters enter the bladder at
ureteric orifices, and the
urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
enters at the
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,
known as
vesicoureteral reflux. Between the two ureteric openings is a raised area of tissue called the interureteric crest.
This makes the upper boundary of the trigone. The trigone is an area of
smooth muscle
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit mus ...
that forms the floor of the bladder above the urethra.
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.
The walls of the bladder have a series of ridges, thick mucosal folds known as
rugae
In anatomy, rugae are a series of ridges produced by folding of the wall of an organ. Most commonly rugae refers to the gastric rugae of the internal surface of the stomach.
Function
A purpose of the gastric rugae is to allow for expansion of ...
that allow for the expansion of the bladder. The
detrusor muscle
The detrusor muscle, also detrusor urinae muscle, muscularis propria of the urinary bladder and (less precise) muscularis propria, is smooth muscle found in the wall of the bladder. The detrusor muscle remains relaxed to allow the bladder to stor ...
is the muscular layer of the wall made of
smooth muscle
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit mus ...
fibers
Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporate ...
arranged in spiral, longitudinal, and circular bundles.
The detrusor muscle is able to change its length. It can also contract for a long time whilst
voiding, and it stays relaxed whilst the bladder is filling.
The wall of the urinary bladder is normally 3–5 mm thick.
When well distended, the wall is normally less than 3 mm.
Nearby structures
![Prostatelead](https://upload.wikimedia.org/wikipedia/commons/a/a1/Prostatelead.jpg)
In men, the
prostate gland
The prostate is both an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, chemically, and physio ...
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
The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus muscle, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the lev ...
and behind the
pubic symphysis. In men, it lies in front of the rectum, separated by the
recto-vesical pouch
The rectovesical pouch is the pocket that lies between the rectum and the bladder in males in humans and other mammals. It is lined by peritoneum.
Structure
The rectovesical pouch is a space between the rectum and the bladder in men. It lies ab ...
, and is supported by fibres of the
levator ani and of the prostate gland. In women, it lies in front of the
uterus
The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...
, separated by the
vesico-uterine pouch, and is supported by the elevator ani and the upper part of the vagina.
[Page 12]
in:
Blood and lymph supply
The bladder receives blood by the
vesical arteries Vesical arteries are variable in number. They supply the bladder and terminal ureter. The two most prominent are the superior vesical artery and the inferior vesical artery. The superior vesical artery comes off of the internal iliac artery and some ...
and drained into a network of
vesical veins
The vesical veins are veins in the pelvis that drain blood from the urinary bladder. The vesical veins receive blood from the vesical venous plexus
The vesical plexus envelops the lower part of the bladder and the base of the prostate
The ...
.
The
superior vesical artery
The superior vesical artery supplies numerous branches to the upper part of the bladder. This artery often also gives branches to the vas deferens and can provide minor collateral circulation for the testicles.
Anatomy
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.
In females, the
uterine and
vaginal arteries
The vaginal artery is an artery in females that supplies blood to the vagina and the base of the bladder.
Structure
The vaginal artery is usually a branch of the internal iliac artery. Some sources say that the vaginal artery can arise from the ...
provide additional blood supply.
Venous drainage begins in a network of small vessels on the lower surfaces of the bladder, which coalesce and travel with the lateral ligaments of the bladder into the
internal iliac veins.
The
lymph
Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to ...
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.
Nerve supply
The bladder receives both sensory and motor supply from
sympathetic and the
parasympathetic nervous system
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...
s.
The motor supply from both sympathetic fibers, most of which arise from the
superior
Superior may refer to:
*Superior (hierarchy), something which is higher in a hierarchical structure of any kind
Places
*Superior (proposed U.S. state), an unsuccessful proposal for the Upper Peninsula of Michigan to form a separate state
*Lake ...
and
inferior hypogastric plexus
The inferior hypogastric plexus (pelvic plexus in some texts) is a network () of nerves that supplies the organs of the pelvic cavity. The inferior hypogastric plexus gives rise to the prostatic plexus in males and the uterovaginal plexus in female ...
es and nerves, and from parasympathetic fibers, which come from the
pelvic splanchnic nerves
Pelvic splanchnic nerves or nervi erigentes are splanchnic nerves that arise from sacral spinal nerves S2, S3, S4 to provide parasympathetic innervation to the organs of the pelvic cavity.
Structure
The pelvic splanchnic nerves arise from t ...
.
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.
These travel via
sacral nerves
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the ...
to
S2-4.
From here, sensation travels to the
brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a v ...
via the
dorsal columns
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
in the
spinal cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...
.
Microanatomy
When
viewed under a microscope the bladder can be seen to have an inner lining (called
epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
), three layers of muscle fibres, and an outer
adventitia.
The inner wall of the bladder is called
urothelium
Transitional epithelium also known as urothelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears ...
, a type of
transitional epithelium
Transitional epithelium also known as urothelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears ...
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.
Additionally, these are lined with a
mucous membrane consisting of a surface
glycocalyx
The glycocalyx, also known as the pericellular matrix, is a glycoprotein and glycolipid covering that surrounds the cell membranes of bacteria, epithelial cells, and other cells. In 1970, Martinez-Palomo discovered the cell coating in animal cells ...
that protects the cells beneath it from urine.
The epithelium lies on a thin
basement membrane
The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between Epithelium, epithelial tissues including mesot ...
, and a
lamina propria
The lamina propria is a thin layer of connective tissue that forms part of the moist linings known as mucous membranes or mucosae, which line various tubes in the body, such as the respiratory tract, the gastrointestinal tract, and the urogenita ...
.
The mucosal lining also offers a urothelial barrier against the passing of infections.
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.
The outside of the bladder is protected by a
serous membrane called
adventitia.
File:Gray1141.png, Vertical section of bladder wall
File:Urinary bladder.JPG, Layers of the urinary 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
Development
In the developing embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
, at the hind end lies a cloaca
In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...
. This, over the fourth to the seventh week, divides into a urogenital sinus
The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh we ...
and the beginnings of the anal canal
The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional segment ...
, with a wall forming between these two inpouchings called the urorectal septum
The urorectal septum is an invagination of the cloaca. It divides it into a dorsal part (the hindgut) and a ventral part (the urogenital sinus). It invaginates from cranial to caudal, formed from the endodermal cloaca, and fuses with the cloacal ...
. The urogenital sinus divides into three parts, with the upper and largest part becoming the bladder; the middle part becoming the urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
, and the lower part changes depending on the biological sex of the embryo.
The human urinary bladder derives from the urogenital sinus
The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh we ...
, and it is initially continuous with the allantois
The allantois (plural ''allantoides'' or ''allantoises'') is a hollow sac-like structure filled with clear fluid that forms part of a developing amniote's conceptus (which consists of all embryonic and extraembryonic tissues). It helps the embryo ...
. The upper and lower parts of the bladder develop separately and join together around the middle part of development. At this time the ureters move from the mesonephric duct
The mesonephric duct (also known as the Wolffian duct, archinephric duct, Leydig's duct or nephric duct) is a paired Organ (anatomy), organ that forms during the embryonic development of humans and other mammals and gives rise to male Sex organ, r ...
s to the trigone. 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
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...
by the recto-vesical pouch
The rectovesical pouch is the pocket that lies between the rectum and the bladder in males in humans and other mammals. It is lined by peritoneum.
Structure
The rectovesical pouch is a space between the rectum and the bladder in men. It lies ab ...
. 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
The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...
by the vesico-uterine pouch. In infants
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
and young children the urinary bladder is in the abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
even when empty.
Function
Urine
Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra.
Cel ...
, excreted by the kidney
The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blood ...
s, collects in the bladder because of drainage from two ureters, before disposal by urination (micturition). Urine leaves the bladder via the urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
, a single muscular tube ending in an opening called the urinary meatus
The urinary meatus, (, ) also known as the external urethral orifice, is the opening of the urethra. It is the point where urine exits the urethra in both sexes and where semen exits the urethra in males. The meatus has varying degrees of sensiti ...
, where it exits the body. Urination involves coordinated muscle changes involving a reflex based in the spine, with higher
Higher may refer to:
Music
* The Higher, a 2002–2012 American pop rock band
Albums
* ''Higher'' (Ala Boratyn album) or the title song, 2007
* ''Higher'' (Ezio album) or the title song, 2000
* ''Higher'' (Harem Scarem album) or the title song ...
inputs from the brain. During urination, the detrusor muscle contracts, and the external urinary sphincter and muscles of the perineum relax, allowing urine to pass through the urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
and out of the body.
The urge to pass urine stems from stretch receptors that activate when between 300 - 400 mL urine is held within the bladder. As urine accumulates, the rugae
In anatomy, rugae are a series of ridges produced by folding of the wall of an organ. Most commonly rugae refers to the gastric rugae of the internal surface of the stomach.
Function
A purpose of the gastric rugae is to allow for expansion of ...
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. Urination is controlled by the pontine micturition center
The Pontine micturition center (PMC, also known as Barrington's nucleus) is a collection of neuronal cell bodies located in the rostral pons in the brainstem involved in the supraspinal regulation of micturition. When activated, the PMC relaxes th ...
in the brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is cont ...
.
Stretch receptors in the bladder signal the parasympathetic
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of t ...
nervous system to stimulate the muscarinic receptor
Muscarinic acetylcholine receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled receptor complexes in the cell membranes of certain neurons and other cells. They play several roles, including acting as the main end-rec ...
s in the detrusor to contract the muscle when the bladder is distended. This encourages the bladder to expel urine through the urethra. The main receptor activated is the M3 receptor
The muscarinic acetylcholine receptor, also known as cholinergic/acetylcholine receptor M3, or the muscarinic 3, is a muscarinic acetylcholine receptor encoded by the human gene CHRM3.
The M3 muscarinic receptors are located at many places in t ...
, although M2 receptors
The muscarinic acetylcholine receptor M2, also known as the cholinergic receptor, muscarinic 2, is a muscarinic acetylcholine receptor that in humans is encoded by the ''CHRM2'' gene. Multiple alternatively spliced transcript variants have been ...
are also involved and whilst outnumbering the M3 receptors they are not so responsive.
The main relaxant pathway is via the adenylyl cyclase
Adenylate cyclase (EC 4.6.1.1, also commonly known as adenyl cyclase and adenylyl cyclase, abbreviated AC) is an enzyme with systematic name ATP diphosphate-lyase (cyclizing; 3′,5′-cyclic-AMP-forming). It catalyzes the following reaction:
:A ...
cAMP
Camp may refer to:
Outdoor accommodation and recreation
* Campsite or campground, a recreational outdoor sleeping and eating site
* a temporary settlement for nomads
* Camp, a term used in New England, Northern Ontario and New Brunswick to descri ...
pathway, activated via the β3 adrenergic receptors. The 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.
Clinical significance
Inflammation and infection
Cystitis refers to infection or inflammation of the bladder. It commonly occurs as part of a urinary tract infection
A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...
. In adults, it is more common in women than men, owing to a shorter urethra
The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...
. It is common in males during childhood, and in older men where an enlarged prostate may cause urinary retention. Other risk factors include other causes of blockage or narrowing, such as prostate cancer
Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...
or the presence of vesico-ureteric reflux; the presence of outside structures in the urinary tract, such as urinary catheters; and neurologic problems that make passing urine difficult. 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 pass urine frequently and with little warning ( urinary urgency). Infections are usually due to bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
, of which the most common is E coli
''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...
.
When a urinary tract infection or cystitis is suspected, a medical practitioner
A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
may request a urine sample
A urine test is any medical test performed on a urine specimen. The analysis of urine is a valuable diagnostic tool because its composition reflects the functioning of many body systems, particularly the kidneys and urinary system, and specimens a ...
. A dipstick placed in the urine may be used to see if the urine has white blood cells
White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
, or the presence of nitrates
Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble ...
which may indicate an infection. The urine specimen may be also sent for microbial culture and sensitivity
Antibiotic sensitivity testing or antibiotic susceptibility testing is the measurement of the wikt:susceptible#Adjective, susceptibility of bacteria to antibiotics. It is used because bacteria may have Antimicrobial resistance, resistance to some ...
to assess if a particular bacteria grows in the urine, and identify its antibiotic sensitivities. 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 a ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
, and testing for an enlarged prostate with a digital rectal examination
Digital rectal examination (DRE; la, palpatio per anum, PPA) is an internal examination of the rectum, performed by a healthcare provider. Prior to a 2018 report from the U.S. Preventive Services Task Force, the DRE was a common and "dreaded" co ...
.
Urinary tract infections or cystitis are treated with antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
s, many of which are consumed by mouth. Serious infections may require treatment with intravenous
Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrie ...
antibiotics.
Interstitial cystitis refers to a condition in which the bladder is infected due to a cause that is not bacteria.
Incontinence and retention
Frequent urination can be due to excessive urine production, small bladder capacity, irritability or incomplete emptying. Males with an enlarged prostate
Benign prostatic hyperplasia (BPH), also called prostate enlargement, is a noncancerous increase in size of the prostate gland. Symptoms may include frequent urination, trouble starting to urinate, weak stream, inability to urinate, or loss o ...
urinate more frequently. One definition of an overactive bladder
Overactive bladder (OAB) is a condition where there is a frequent feeling of needing to urinate to a degree that it negatively affects a person's life. The frequent need to urinate may occur during the day, at night, or both. If there is loss ...
is when a person urinates more than eight times per day. 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, it is not entirely clear how these are disturbed in the overactive bladder. Urodynamic testing
Urodynamic testing or urodynamics is a study that assesses how the bladder and urethra are performing their job of storing and releasing urine. Urodynamic tests can help explain symptoms such as:
* incontinence
* frequent urination
* sudden, stro ...
can help to explain the symptoms. An underactive bladder
Underactive bladder syndrome (UAB) describes symptoms of difficulty with bladder emptying, such as hesitancy to start the stream, a poor or intermittent stream, or sensations of incomplete bladder emptying. The physical finding of detrusor activ ...
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 stones.
Disorders of or related to the bladder include:
* Bladder exstrophy
Bladder exstrophy is a congenital anomaly that exists along the spectrum of the exstrophy-epispadias complex, and most notably involves protrusion of the urinary bladder through a defect in the abdominal wall. Its presentation is variable, often ...
* Bladder sphincter dyssynergia
Bladder sphincter dyssynergia (also known as detrusor sphincter dyssynergia (DSD) (the ICS standard terminology agreed 1998) and neurogenic detrusor overactivity (NDO)) is a consequence of a neurological pathology such as spinal injury or multip ...
, a condition in which the sufferer cannot coordinate relaxation of the urethra sphincter with the contraction of the bladder muscles
* Paruresis
* Trigonitis
Trigonitis is a condition of inflammation of the trigone region of the bladder. It is more common in women.
The cause of trigonitis is not known, and there is no solid treatment. Electrocautery is sometimes used, but is generally unreliable as a ...
* Underactive bladder
Underactive bladder syndrome (UAB) describes symptoms of difficulty with bladder emptying, such as hesitancy to start the stream, a poor or intermittent stream, or sensations of incomplete bladder emptying. The physical finding of detrusor activ ...
, a condition with its main symptom being urinary retention.
Disorders of bladder function may be dealt with surgically, by re-directing the flow of urine or by replacement with an artificial urinary bladder
The two main methods for replacing bladder function involve either redirecting urine flow or replacing the bladder ''in situ''. Replacement can be done with an artificial urinary bladder, an artificial organ.
Development
On January 30, 1999, scie ...
. The volume of the bladder may be increased by bladder augmentation
Bladder augmentation is a surgical alteration of the urinary bladder. It involves removing strips of tissue from the intestinal tract and adding this to the tissue of the bladder. This has two intended results: increased bladder volume; and ...
. An obstruction of the bladder neck may be severe enough to warrant surgery.
Cancer
Cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
of the bladder is known as bladder cancer
Bladder cancer is any of several types of cancer arising from the tissues of the urinary bladder. Symptoms include blood in the urine, pain with urination, and low back pain. It is caused when epithelial cells that line the bladder become mali ...
. It is usually due to cancer of the urothelium
Transitional epithelium also known as urothelium is a type of stratified epithelium. Transitional epithelium is a type of tissue that changes shape in response to stretching (stretchable epithelium). The transitional epithelium usually appears ...
, 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; other risk factors include smoking
Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...
and exposure to dye
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution an ...
s such as aromatic amines and aldehydes.[ When cancer is present, the most common symptom in an affected person is blood in the urine; a physical ]medical examination
In a physical examination, medical examination, or clinical examination, a medical practitioner examines a patient for any possible medical signs or symptoms of a medical condition. It generally consists of a series of questions about the patient ...
may be otherwise normal, except in late disease. Bladder cancer is most often due to cancer of the cells lining the ureter, called transitional cell carcinoma
Transitional cell carcinoma, also called urothelial carcinoma, is a type of cancer that typically occurs in the urinary system. It is the most common type of bladder cancer and cancer of the ureter, urethra, and urachus. It accounts for 95% of ...
, although it can more rarely occur as a squamous cell carcinoma
Squamous-cell carcinomas (SCCs), also known as epidermoid carcinomas, comprise a number of different types of cancer that begin in squamous cells. These cells form on the surface of the skin, on the lining of hollow organs in the body, and on the ...
if the type of cells lining the urethra have changed due to chronic inflammation, such as due to stones or schistosomiasis
Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody s ...
.
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
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
by a CT urogram or ultrasound
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
. 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
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
, and a CT scan
A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...
will be performed of other body parts (a CT scan of the chest, abdomen and pelvis) to look for additional lesions.
Treatment depends on the cancer's stage. Cancer present only in the bladder may be removed surgically via cystoscopy; an injection of the chemotherapeutic
Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...
mitomycin C may be performed at the same time. Cancers that are 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. Cancer that is invading through the bladder wall may be managed by complete surgical removal of the bladder (radical cystectomy
Cystectomy is a medical term for surgery, surgical removal of all or part of the urinary bladder. It may also be rarely used to refer to the removal of a cyst. The most common condition warranting removal of the urinary bladder is bladder cancer. ...
), with the ureters diverted into a segment of part of ileum connected to a stoma bag
An ostomy pouching system is a prosthetic medical device that provides a means for the collection of waste from a surgically diverted biological system ( colon, ileum, bladder) and the creation of a stoma. Pouching systems are most commonly asso ...
on the skin. 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 don't invade through the bladder wall, and that is in visual appearance.
Investigation
A number of investigations are used to examine the bladder. The investigations that are ordered will depend on the taking of a medical history
The medical history, case history, or anamnesis (from Greek: ἀνά, ''aná'', "open", and μνήσις, ''mnesis'', "memory") of a patient is information gained by a physician by asking specific questions, either to the patient or to other peo ...
and an examination. The examination may involve a medical practitioner
A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
feeling in the suprapubic area for tenderness or fullness that might indicate an inflamed or full bladder. Blood tests may be ordered that may indicate inflammation; for example a full blood count may demonstrate elevated white blood cell
White blood cells, also called leukocytes or leucocytes, are the cell (biology), cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and de ...
s, or a C-reactive protein may be elevated in an infection.
Some forms of medical imaging
Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to rev ...
exist to visualise the bladder. A bladder ultrasound
The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
may be conducted to view how much urine is within the bladder, indicating urinary retention. A urinary tract ultrasound
Ultrasound of the urinary tract involves the use of an ultrasound probe to image parts of the urinary tract. The urinary tract is the path that urine follows after it is formed within the kidneys, and involves a left and right ureter, the bladder, ...
, 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 CT scan
A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...
may also be ordered.
A flexible internal camera, called a cystoscope
Cystoscopy is endoscopy of the urinary bladder via the urethra. It is carried out with a cystoscope.
The urethra is the tube that carries urine from the bladder to the outside of the body.
The cystoscope has lenses like a telescope or microscope ...
, can be inserted to view the internal appearance of the bladder and take a biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
if required.
Urodynamic testing
Urodynamic testing or urodynamics is a study that assesses how the bladder and urethra are performing their job of storing and releasing urine. Urodynamic tests can help explain symptoms such as:
* incontinence
* frequent urination
* sudden, stro ...
can help to explain the symptoms.
Other animals
Mammals
All mammals have a urinary bladder. This structure begins as an embryonic cloaca
The cloaca is a structure in the development of the urinary and reproductive organs.
The hind-gut is at first prolonged backward into the body-stalk as the tube of the allantois; but, with the growth and flexure of the tail-end of the embryo, ...
. In the vast majority, this eventually becomes differentiated into a dorsal part connected to the intestine and a ventral part which becomes associated with the urinogenital passage and urinary bladder. The only mammals in which this does not take place are the platypus
The platypus (''Ornithorhynchus anatinus''), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal Endemic (ecology), endemic to Eastern states of Australia, eastern Australia, including Tasmania. The platypu ...
and the spiny anteater
Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...
both of which retain the cloaca into adulthood.
The mammalian bladder is an organ that regularly stores a hyperosmotic concentration of urine. It therefore is relatively impermeable and has multiple epithelial layers. The urinary bladder of the cetacean
Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel them ...
s (whales and dolphins) is proportionally smaller than that of land-dwelling mammals.
Reptiles
In all reptiles, the urinogenital ducts and the anus
The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, d ...
both empty into an organ called a cloaca
In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...
. In some reptiles, a midventral wall in the cloaca may open into a urinary bladder, but not all. It is present in all turtles and tortoises as well as most lizards but is lacking in the monitor lizard
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recogn ...
, the legless lizards. It is absent in the snakes, alligators, and crocodiles.
Many turtles, tortoises, and lizards have proportionally very large bladders. Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
noted that the Galapagos tortoise had a bladder which could store up to 20% of its body weight. Such adaptations are the result of environments such as remote islands and deserts where water is very scarce. Other desert-dwelling reptiles have large bladders that can store a long-term reservoir of water for up to several months and aid in osmoregulation.
Turtles have two or more accessory urinary bladders, located lateral to the neck of the urinary bladder and dorsal to the pubis, occupying a significant portion of their body cavity. Their bladder is also usually bilobed with a left and right section. The right section is located under the liver, which prevents large stones from remaining in that side while the left section is more likely to have calculi.
Amphibians
Most aquatic and semi-aquatic amphibians have a membranous skin which allows them to absorb water directly through it. Some semi-aquatic animals also have similarly permeable bladder membrane. As a result, they tend to have high rates of urine production to offset this high water intake, and have urine which is low in dissolved salts. The urinary bladder assists such animals to retain salts. Some aquatic amphibian such as ''Xenopus
''Xenopus'' () (Gk., ξενος, ''xenos''=strange, πους, ''pous''=foot, commonly known as the clawed frog) is a genus of highly aquatic frogs native to sub-Saharan Africa. Twenty species are currently described within it. The two best-known ...
'' do not reabsorb water, to prevent excessive water influx. For land-dwelling amphibians, dehydration results in reduced urine output.
The amphibian bladder is usually highly distensible and among some land-dwelling species of frogs and salamanders may account for between 20% and 50% of their total body weight.
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 teleosts is permeable to water, though this is less true for freshwater dwelling species than saltwater species. Most fish also have an organ called a swim-bladder
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth wit ...
which is unrelated to the urinary bladder except in its membranous nature. The loaches, pilchard
"Sardine" and "pilchard" are common names for various species of small, Oily fish, oily forage fish in the herring family Clupeidae. The term "sardine" was first used in English during the early 15th century, a folk etymology says it comes fr ...
s, and herring
Herring are forage fish, mostly belonging to the family of Clupeidae.
Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...
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 oviducts and behind the rectum
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...
. The urinary bladders of fish and tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...
s are thought to be analogous while the former's swim-bladders and latter's lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
s are considered homologous.
Birds
In nearly all bird species, there is no urinary bladder per se. Although all birds have kidneys, the ureters open directly into a cloaca
In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...
which serves as a reservoir for urine, fecal matter, and eggs.
Crustaceans
Unlike the urinary bladder of vertebrates, the urinary bladder of crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s both stores and modifies urine. 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. The tissue of the bladder is thin epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
.
See also
* Alpha blocker
Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , which ...
* Cystitis glandularis
Cystitis glandularis is the transformation of mucosal cells lining the urinary bladder. They undergo glandular metaplasia, a process in which irritated tissues take on a different form, in this case that of a gland. The main importance is in the ...
* UPK1B
References
;Books
*
*
External links
* – "Mammal, bladder (LM, Medium)"
Bladder
() – An open-access journal on bladder biology and diseases.
{{Use dmy dates, date=April 2017
Pelvis
Organs (anatomy)
Urinary system