ureter n : either of a pair of thick-walled tubes that carry urine from the kidney to the urinary bladder
Nounureter (plural: ureters)
In human anatomy, the ureters are muscular ducts that propel urine from the kidneys to the urinary bladder. In the adult, the ureters are usually 25-30cm (10-12 inches)long.
In humans, the ureters arise from the renal pelvis on the medial aspect of each kidney before descending towards the bladder on the front of the psoas major muscle. The ureters cross the pelvic brim near the bifurcation of the iliac arteries (which they run over). This "pelviureteric junction" is a common site for the impaction of kidney stones (the other being the ureterovesical valve). The ureters run posteroinferiorly on the lateral walls of the pelvis. They then curve anteriormedially to enter the bladder through the back, at the vesicoureteric junction, running within the wall of the bladder for a few centimeters. The backflow of urine is prevented by valves known as ureterovesical valves, pressure from the filling of the bladder, and the tone of the muscle in the bladder wall.
HistologyThe ureter has a diameter of about 3 millimeters, and the lumen is star-shaped. Like the bladder, it is lined with transitional epithelium, and contains layers of smooth muscle, thereby being under autonomic control.
The epithelial cells of the ureter are stratified (in many layers), are normally round in shape but become squamous (flat) when stretched. The lamina propria is thick and elastic (as it is important that it is impermeable).
There are two spiral layers of smooth muscle in the ureter wall, an inner loose spiral, and an outer tight spiral. The inner loose spiral is sometimes described as longitudinal, and the outer as circular, (this is the opposite to the situation in the gastrointestinal tract). The distal third of the ureter contains another layer of outer longitudinal muscle.
The adventitia of the ureter, like elsewhere is composed of fibrous connective tissue, that binds it to adjacent tissues.
Diseases and disordersMedical problems that can affect the ureter include:
- - "Posterior Abdominal Wall: Internal Structure of a Kidney"
- - "Relationship of the ureter to the uterine artery."
- - "Mid-sagittal section of male pelvis."
- - "Mammal, ureter (LM, Medium)"
- - "Ureter"
Image:Illu bladder.jpg|Bladder Image:Illu kidney2.jpg|Frontal section through the kidney Image:Illu ureters wall.jpg|Wall of the ureter.
ureter in Arabic: حالب
ureter in Bulgarian: Пикочопровод
ureter in Czech: Močovod
ureter in German: Harnleiter
ureter in Dhivehi: ގުރުތާ
ureter in Spanish: Uréter
ureter in French: Uretère
ureter in Korean: 수뇨관
ureter in Indonesian: Ureter
ureter in Italian: Uretere
ureter in Hebrew: שופכן
ureter in Kurdish: Mîzlûl
ureter in Lithuanian: Šlapimtakis
ureter in Dutch: Urineleider
ureter in Japanese: 尿管
ureter in Norwegian: Urinleder
ureter in Polish: Moczowód
ureter in Portuguese: Ureter
ureter in Russian: Мочеточник
ureter in Slovak: Močovod
ureter in Slovenian: Sečevod
ureter in Serbian: Мокраћовод
ureter in Serbo-Croatian: Mokraćovod
ureter in Finnish: Virtsanjohdin
ureter in Telugu: మూత్రనాళం