Urinary bladder

From Wikipedia, the free encyclopedia

Urinary bladder

Urinary system.

Bladder
Latin	vesica urinaria
Gray's	subject #255 1227
Artery	Superior vesical artery Inferior vesical artery Umbilical artery Vaginal artery
Vein	Vesical venous plexus
Nerve	Vesical nervous plexus
Lymph	external iliac lymph nodes, internal iliac lymph nodes
Precursor	urogenital sinus
MeSH	Bladder
Dorlands/Elsevier	v_07/12855244

In the anatomy of mammals, the urinary bladder is a hollow, muscular and distensible or elastic organ that sits on the pelvic floor. It is the organ that collects urine excreted by the kidneys prior to disposal by urination. Urine enters the bladder via the ureters and exits via the urethra.

1 Relations
2 Regions
3 Wall
4 Detrusor muscle
5 Diseases of the bladder
6 See also
7 External links
8 Additional images

[edit] Relations

On its anterior border lies the pubic symphysis and, on its posterior border, the vagina (in females) and rectum (in males).

In males, the bladder is superior to the prostate, and separated from the rectum by the rectovesical excavation.

In females, the bladder is separated from the rectum by the rectouterine excavation, and it is separated from the uterus by the vesicouterine excavation.

[edit] Regions

Trigone: The ureters enter the bladder diagonally from its dorsolateral floor in an area called the trigone, which is a triangular shaped area on the postero-inferior wall of the bladder. The urethra exits at the lowest point of the triangle of the trigone.
Apex: The Median umbilical ligament connects to the apex of the bladder.
Neck: The Neck is connected to the pubic bone by the pubovesical ligament in women, and by the puboprostatic ligament in men.

[edit] Wall

The wall of the urinary bladder consists of three layers:

Mucosa	in this instance transitional epithelium & lamina propria
Detrusor muscle	consists of an inner and outer longitudinal layer and a middle circular layer of smooth muscle
a fibrous adventitia and the visceral peritoneum	lie on superior surface

[edit] Detrusor muscle

The detrusor muscle is a layer of the urinary bladder wall, made up of smooth muscle fibers. When the bladder is stretched, this signals the parasympathetic nervous system to cause contraction of the detrusor muscle. This then encourages the bladder to expel urine through the urethra.

For the urine to finally exit the bladder, both the autonomically controlled internal sphincter and the voluntarily controlled external sphincter must be opened. Problems with these muscles can lead to incontinence.

The urinary bladder can hold approximately 17 to 18 ounces (500 to 530 ml) of urine, however the desire to micturate is usually experienced when it contains about 5 to 7 ounces (150 to 200 ml).

The study of the functional aspects of the detrusor muscle is urodynamics.

[edit] Diseases of the bladder

Bladder sphincter dyssynergia, a condition where the sufferer cannot coordinate relaxation of the urethra sphincter with the contraction of the bladder muscles
Cystitis
Cancer of the urinary bladder: bladder cancer
Hematuria, or presence of blood in the urine, is a reason to seek medical attention without delay, as it is a symptom of bladder cancer as well as bladder and kidney stones.
Interstitial cystitis
Paruresis, a phobia which causes difficulty to urinate in public
Ureterocele
Urinary incontinence
Vesicouretic Reflux
Trigonitis

[edit] See also

[edit] External links

Histology at KUMC epithel-epith09 "Urinary Bladder"
Organology at UC Davis Urinary/mammal/bladder/bladder1 - "Mammal, bladder (LM, Medium)"
Virtual Slidebox at Univ. Iowa Slide 445
SUNY Labs 43:07-0100 - "The Female Pelvis: The Urinary bladder"
SUNY Labs 44:04-0103 - "The Male Pelvis: The Urinary bladder"

[edit] Additional images

Structure of the penis	Organs of the female reproductive system.	Coronal section of pelvis, showing arrangement of fasciæ. Viewed from behind.	Dissection of side wall of pelvis showing sacral and pudendal plexuses. (Bladder visible at lower left.) \|
The peritoneum of the male pelvis.	Median sagitta section of male pelvis.	Male pelvic organs seen from right side.	Median sagittal section of female pelvis.
The interior of bladder.	Vertical section of bladder wall.	Fundus of the bladder with the vesiculæ seminales.	Vertical section of bladder, penis, and urethra.
Female pelvis and its contents, seen from above and in front.	Topography of thoracic and abdominal viscera.