Ureter

Your body has two small tubes.

These tubes carry liquid from your kidneys. The liquid goes to your bladder.

The tubes have muscles. These muscles squeeze in a rhythm. This squeezing moves the liquid down. It works like a pump.

Sometimes, small hard bits can get stuck. These are called kidney stones. They can cause a sharp pain.

Doctors can see the tubes. They use special tools like X-rays. They can also use a tiny camera.

It is good to learn how your body works!

Your body has two tubes called ureters.

They carry urine from your kidneys to your bladder. In adults, these tubes are 20 to 30 centimeters long. They are very thin, only 3 to 4 millimeters wide.

The ureters move urine using a set of steps. The muscles in the tube walls squeeze in a rhythm. This is called peristalsis. This squeezing pushes the urine down to the bladder. The tubes are lined with urothelium. This is a special layer of cells that can stretch.

Sometimes, small hard bits called kidney stones can form.

A stone can get stuck inside a ureter. This can block the urine and cause sharp pain. The pain can move to your back or sides. Doctors can use X-rays or ultrasound to see the tubes. They can also use a tiny camera to look inside. This tool is called a ureteroscope. It was first described in 1964.

The ureters are two important tubes in your urinary system.

Their main job is to carry urine from the kidneys to the bladder. In adult humans, these tubes are usually 20 to 30 centimeters long. They are quite thin, with a diameter of only 3 to 4 millimeters.

These tubes are vital for moving waste out of the body. Without them, urine could not reach the bladder to be stored.

To move urine, the ureters use a special way of working called peristalsis. This means the smooth muscles in the tube walls squeeze in a regular rhythm. These contractions push the urine downward toward the bladder. The inside of the tube is lined with urothelium. This is a type of transitional epithelium, which is a layer of cells that can stretch.

When the tube stretches, these cells can change from a tall shape to a flatter shape.

People have known about the ureters for a very long time. The name comes from a word root related to urinating. We have seen this word in written records since the time of Hippocrates. However, the specific name "ureter" has only been used consistently since the 16th century. In 1964, doctors described a way to look inside using a flexible camera called a ureteroscope.

Today, we use modern tools like X-rays, CT scans, and ultrasound to see them clearly.

Sometimes, small hard pieces called kidney stones can form.

These stones are often made of calcium, such as calcium oxalate. A stone can get stuck in the ureter and block the flow of urine. This can cause a sharp pain called renal colic. The pain often comes in waves that last up to two hours. If a stone blocks the tube, the kidney might swell up, which is called hydronephrosis.

In children, urine sometimes flows backward from the bladder into the ureters. This is called vesicoureteral reflux. It is a common condition that affects about 28 to 36 percent of children. Doctors use different tools, like ultrasound, to check for this. Most of the time, this condition gets better on its own. Understanding how these tubes work helps doctors keep our bodies healthy and running well.

The ureters are essential tubular structures in the human urinary system. Their primary function is to transport urine from the kidneys to the urinary bladder. In adult humans, these tubes are typically 20 to 30 centimeters long. They are quite narrow, usually measuring only 3 to 4 millimeters in diameter.

Because they connect the kidneys to the bladder, they are vital for waste removal. Without them, urine could not reach the bladder for storage and eventual excretion.

To move urine, the ureters utilize a process called peristalsis. This mechanism involves regular contractions of the smooth muscle within the tube walls. These rhythmic squeezes push the urine downward toward the bladder. The ureters are composed of several distinct layers. The innermost layer is the urothelium, a type of transitional epithelium. This lining is special because it can respond to stretching. When the ureter is relaxed, these cells may appear column-shaped. When the tube is distended, the cells become flatter.

Below this lining sits the lamina propria, which is loose connective tissue containing elastic fibers and blood vessels. The muscle layer consists of an inner longitudinal layer and an outer circular or spiral layer. Interestingly, the lower third of the ureter features an extra layer of smooth muscle to assist with peristalsis.

The path of the ureter is complex as it travels through the body. It begins at the renal pelvis and descends on top of the psoas major muscle. As it moves toward the pelvis, it crosses in front of the common iliac arteries. The ureters eventually enter the bladder at the vesicoureteric junction. This is the point where they open into the bladder through slit-like openings called ureteric orifices. The position of these openings changes depending on whether the bladder is contracted or distended. In a contracted bladder, the orifices are about 2 centimeters apart. In a distended bladder, this distance can increase to about 4 centimeters.

As the ureters descend, they pass near many important anatomical structures. The right ureter passes behind the terminal ileum, while the left ureter sits behind the jejunum and sigmoid colon. In females, the ureters pass behind the ovaries and travel through the broad ligament of the uterus. They even pass by the cervix before entering the bladder. To maintain these tissues, the ureters rely on a specific blood supply. The upper third receives blood from the renal arteries. The middle part is supplied by the common iliac and gonadal arteries. The lower third is fed by branches from the internal iliac arteries.

Medical history shows that humans have recognized the ureters for at least two thousand years. The term itself comes from a word root relating to urination. Written records of the term have existed since the time of Hippocrates. However, the specific name "ureter" was not used consistently until the 16th century. For a long time, doctors could not see the tubes inside a living body. This changed in the 20th century with the development of medical imaging. Techniques like X-ray, CT scans, and ultrasound now allow doctors to view the ureters clearly. In 1964, a new method called ureteroscopy was described, which uses a flexible camera to see inside the tubes.

Various medical conditions can affect how the ureters function. One common issue involves kidney stones, which are often made of calcium compounds like calcium oxalate.

If a stone becomes lodged in the ureter, it can block the flow of urine. This blockage can cause a sharp, cramping pain known as renal colic. This pain often arrives in waves that can last up to two hours. If the blockage is not resolved, the kidney may swell, a condition called hydronephrosis. Another issue is vesicoureteral reflux, where urine flows backward from the bladder into the ureters. This is quite common in children, affecting between 28% and 36% of them.

Finally, the ureters are deeply connected to the body's nervous and lymphatic systems. They are surrounded by a network of nerves called the ureteric plexus. This plexus is located in the adventitia, which is the outermost layer of the ureter. Nerves from various spinal cord segments, such as T11 to L2, provide sensation. Sensation is sparse near the kidneys but increases as you get closer to the bladder. The lymphatic system also drains the ureters through various nodes in the abdomen and pelvis. This complex network of nerves, blood vessels, and lymphatics ensures the ureters can function reliably within the body's larger systems.