Although their functions may appear simple, the ureters perform essential excretory work for the body. These two slender tubes transport urine from the kidneys to the bladder. The ureters use a process called peristalsis, the contracting, rhythmic movement of smooth muscles, to push the urine into the bladder. The organs prevent urine from backing up or standing still, which protects the body from developing kidney and bacterial infections.
The peritoneum is the membrane that lines the abdominal cavity. Like the kidneys, the ureters are retroperitoneal organs, meaning they sit behind this membrane. Each tube is between eight and 12 inches long. The left ureter is slightly longer than the right because the left kidney is located a bit higher than its counterpart. The ureters’ thick walls consist of four layers: the innermost layer--the mucosa, the lining of the mucosa--the submucosa, the smooth muscles that allow ureter movement--the muscularis, and the outmost layer, comprised of loose, connective tissue-- the adventitia.
The ureters start at the tip of the funnel-shaped renal pelves that emerge out of the kidneys. After exiting the kidneys, the ureters run along the anterior or front side of the psoas major muscle that connects the top and lower halves of the body. The ureters then pass over the brim of the pelvis, where the iliac arteries divide into branches. They enter the bladder at its opening from the back or posterior side. The ureter path is different in females, running below the uterine artery.
The kidneys filter the blood and remove one of the end products of human metabolism, urea. As the urea passes through the kidney’s nephrons, it mixes with water and other waste products to create urine, which flows into the ureters. The muscles in the ureter walls contract and relax, forcing the urine down and away from the kidneys. Every 10 to 15 seconds, the ureters deliver urine into the bladder. The bladder holds about one and a half to two cups of urine. When the ureters fill the bladder with urine, the muscles in the bladder wall contract and send messages to the brain that it’s time to find a bathroom.
A variety of arteries are responsible for the ureters’ blood supply. The renal artery supplies blood to the part of the ureter closest to the kidney. The middle part of the ureters receives blood from the iliac arteries, from the testicular artery in men, and the ovarian artery in women. The section of the ureters closest to the bladder obtains its blood supply from the middle rectal artery and the superior vesical artery. Additionally, men receive blood supply to this section through the inferior vesical artery, while women receive it from the vaginal and uterine arteries.
Blockages or ureter injuries can interrupt urine flow or bring it to a complete halt. This can cause bacteria buildup and a urinary tract infection (UTI). Most UTIs occur in the lower urinary tract, in the bladder, or in the urethra. Additionally, UTIs are more likely to affect women. In some cases, the bacteria travel to the upper urinary tract, the ureters, and the kidneys. This can result in more serious infection and illness. A doctor usually prescribes antibiotics to fight the infection.
Sometimes the ureters do not connect properly with the bladder, causing urine to drain outside the bladder rather than into it. In females, the urine drains into the urethra or the vagina. In males, the urine drains into the urethra, but also into the sex organs. This condition often occurs in those born with a kidney that connects to two separate ureters. An ectopic ureter means one of the ureters drains into the bladder, but the other drains outside of it. This condition may cause UTIs and incontinence. An ectopic ureter may also lead to blockages, which can force urine to back up into the kidney.
This condition causes urine to travel back up into the bladder towards the kidney, due to a blockage of the ureter at the ureteropelvic junction where it connects to the kidney. It can also occur at the connection to the bladder, the ureterovesical junction, or in the urethra in boys, the posterior urethral valve. It may affect a single ureter or both. VUR may cause hydronephrosis, a buildup of urine in the kidneys. Doctors can detect this common fetal abnormality as early as the first trimester. VUR can also affect older children and adults who inherit it from their parents.
Injuries to the ureters and kidneys do occur but are rare. Complications during surgical or medical procedures cause the most common types of injuries. Kidney stones form when urine becomes concentrated and crystalizes, and they can lodge anywhere along the urinary tract. When these stones lodge in the ureters, doctors refer to them as ureteral stones. Once lodged, they can block the flow of urine into the bladder. This causes pain in the back and ribs that radiates into the lower abdomen.
A urologist treats diseases and infections of the urinary tract but also specializes in men’s reproductive systems. Urologists have completed four years of college, four years of medical school, then four to five years of residency, training under a licensed urologist. They must then pass a specialty certification exam to become a practicing urologist. Using a combination of diagnostic testing, lab tests, and a physical examination, a urologist makes a diagnosis of conditions occurring in the urinary tract.
Pain upon urination, blood in the urine, pain in the lower back pelvis or sides, and difficulty urinating are signs of a possible infection or other urinary tract issues. If the urologist suspects an issue with the ureters or any other part of the urinary tract, he or she may perform a series of lab tests after collecting urine and blood samples. MRIs, CT scans, or ultrasounds identify blockages, congenital disabilities, and other conditions. The physician may also order a cystogram, an x-ray of the bladder.
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