Ureter - the structure and functions of the urinary system
The ureter is a thin duct that connects the kidney anda bladder, through which urine is excreted from the kidney into the bladder. The structure and functions of the ureters provide normal functioning of the urinary system. Each kidney has its own ureter, which exits the renal pelvis and enters the bladder. The length of each ureter is about 30 cm, the diameter varies from 4 to 7 mm. The size of the ureter is important in urolithiasis. Stones larger than 4 mm can not freely exit with a current of urine into the bladder and lead to the development of renal colic.
Ureter: abdominal and pelvic structure
From the renal pelvis the ureter goes in the directiondown and into the middle and small pelvis, there he enters the bladder, perforating its wall in an oblique direction. In each ureter, the abdominal and pelvic parts are distinguished. The ventral part of the ureter is located in front of the large lumbar muscle. Before the right ureter is the descending section of the duodenum, the vessels and the base of the mesentery of the small intestine. In front of the left there is a duodenum-jejunal bend, a vascular bundle and the base of the mesentery of the sigmoid colon.
In the pelvic part, the ureters pass aheadiliac arteries and veins. The diameter of the ureter in this part is narrowed. In men, it passes from the front of the vas deferens and down into the bladder below the upper pole of the seminal vesicle. In the pelvic part, the ureters in women are surrounded by other organs: the ureter passes along the edge of the ovary and the uterine neck, enters the bladder on the side of the vagina.
The intra-wall is the part of the ureter located inside the wall of the bladder.
Mochetochnik: structure of the wall
The wall of the ureter, as well as the renal pelviswith cups, consists of three shells: the outer one - from the connective tissue, internal, covered from within by a transitional epithelium with mucous glands and the middle one, consisting of two layers of musculature - longitudinal and circular. The musculature of the ureters is not associated with the muscular layer of the bladder and prevents the reverse urine flow from the bladder into the ureter.
In the place of entry of the ureter into the bladder inits wall is a layer of longitudinal muscles, closely related to the muscular layer of the bladder. This layer actively prevents the return of urine to the ureter. The presence of this layer limits the spread of infection from the bladder to the ureter and then into the kidneys.
Ureter: structure of the lumen
The ureteral lumen has several constrictions:
- the first constriction is located in the area of the pelvis transition to the ureter;
- the second is located on the border between the abdominal and pelvic parts;
- the third narrowing can be in any part of the pelvic part;
- The fourth narrowing is located near the wall of the bladder.
The presence of natural narrowing of the ureters hasgreat clinical importance. In these areas, the stones emerging from the renal pelvis and with urine flow are moving in the direction of the bladder.
In the course of the ureter, in addition to anatomical constrictions, there are physiological contractions that appear and disappear during peristalsis.
Mochetochnik: structure of blood supply and innervation
The upper part of the ureter receives blood frombranches branching from renal and testicular or ovarian arterial vessels. The middle part is supplied with blood from the ureteral branches that extend from the abdominal part of the aorta and the iliac arteries. The lower part is from the bladder and middle rectal artery. The outflow of blood occurs in the internal iliac and lumbar veins.
The innervation of the ureter is from the following several vegetative nervous plexuses. The branches of the vagus nerve and the pelvic internal nerves provide parasympathetic innervation.
