Urethra

Your body has a small tube.

It carries pee out of you. This tube starts at your bladder. It moves pee to the outside of your body. In boys, it also carries seeds.

Muscles help control this tube. Some muscles work on their own. Other muscles work when you choose. This helps you decide when to go. It is a very useful part of you.

The urethra is a tube in your body. It carries urine from the bladder to the outside.

In males, it also carries semen. This tube has different parts. It is made of muscle and other tissues.

There are muscles that help control the tube. The internal sphincter is a muscle that works on its own. You cannot tell it what to do. The external urethral sphincter is a striated muscle. This is a muscle you can control. It helps you decide when to go to the bathroom.

In males, the tube is quite long. It can be about 22.3 cm long on average. In females, the tube is much shorter. It is about 4 cm long.

Small glands make mucus. This mucus helps the tube stay slippery. This is called lubrication. Sometimes, germs can get into the tube. This can cause an infection called urethritis. Doctors can treat this with medicine. Small stones can also pass through the tube. This can sometimes cause pain.

The urethra is a very important tube in the body. It acts like a path for urine to leave the bladder. This tube carries urine to the outside of the body through an opening called the meatus. In males, the urethra also carries semen during ejaculation. This tube is made of muscle and other tissues. It is a vital part of how the body stays clean.

How the tube works depends on special muscles. The internal sphincter is a smooth muscle that works on its own. You do not have to think to make it work. The external urethral sphincter is a different kind of muscle. This is a striated muscle that you can control. It helps you decide when it is time to go to the bathroom. When you urinate, the bladder squeezes and the tube muscles relax.

People have studied this tube for a very long time. The word urethra comes from an Ancient Greek word. Long ago, a person named Hippocrates described it. At that time, people used the wrong name for it. They called it the ureter instead. It took until the 1550s for experts to use the right names. People like Bartolomeo Eustachi helped make these names clear.

The tube looks different in males and females. In males, the urethra is quite long. A study of 109 men found it is about 22.3 cm long on average. It has four different parts like the prostatic and spongy urethra. In females, the tube is much shorter. It is usually about 4 cm long. It has a diameter of about 6 mm.

Sometimes, the urethra can have health problems. An infection in the tube is called urethritis. This can be caused by many different germs or viruses. Small stones can also move through the tube, which might cause pain. Doctors can use a tiny camera to look inside the tube. This tool is called a urethroscopy. They can also use medicine to help if there is an infection.

The urethra is a vital muscular tube in placental mammals. It serves as the primary channel for transporting urine from the bladder to the outside of the body. This exit point is known as the urethral meatus. In males, the urethra serves an additional purpose. It also acts as a conduit for semen during the process of ejaculation. This tube is essential for waste removal and maintaining bodily health.

To manage the flow of urine, the body uses two distinct types of muscles. The internal sphincter is made of involuntary smooth muscle. It lines the neck of the bladder and controls itself automatically. The external urethral sphincter is a striated muscle. This muscle allows for voluntary control, meaning you can decide when to urinate. During urination, the bladder contracts to push liquid out. Simultaneously, the smooth muscles of the urethra relax to allow passage. Afterward, the muscles contract again to restore tone.

The structure of the male urethra is complex and divided into four specific regions. First is the pre-prostatic urethra, which is the intramural part near the bladder. It measures between 0.5 and 1.5 cm depending on bladder fullness. Next is the prostatic urethra, which crosses through the prostate gland. This area contains several important openings, including the ejaculatory ducts and prostatic ducts. The third part is the membranous urethra. This is the narrowest section, measuring only 1 to 2 cm. Finally, the spongy urethra runs through the length of the penis. It is much longer, typically between 15 and 25 cm.

In females, the urethra is significantly different in both length and location. It is much shorter, measuring approximately 4 cm in length. It has a diameter of about 6 mm. The female urethra exits the body between the clitoris and the vaginal opening. It is positioned behind the symphysis pubis and curves slightly downward and forward. The lining of the female urethra changes along its path. The proximal two-thirds are lined with transitional epithelial cells. The distal third is lined with stratified squamous epithelial cells.

Understanding the microscopic makeup of the urethra reveals how it protects the body. The lining, or epithelium, consists of various cell types. Near the bladder, transitional cells change shape based on pressure. As the tube reaches the exit, the lining becomes multiple layers of flat cells. This transition matches the external skin. Small glands, such as the bulbourethral glands of Cowper, provide mucus. This mucus acts as a lubricant for the tube. The urethra itself is built from three layers: muscular, erectile, and mucous.

Medical science has long studied these structures. The term "urethra" originates from the Ancient Greek word "ourḗthrā." During the time of Hippocrates, the term "ureter" was often used incorrectly to describe it. It was not until the 1550s that anatomists like Bartolomeo Eustachi and Jacques Dubois clarified the names. They helped distinguish the urethra from the ureter. Since then, many specific medical terms have emerged. For example, urethritis refers to an infection of the urethra. This can be caused by bacteria, such as chlamydia, or by various viruses.

Health issues can sometimes affect the urethra's function. Infections like urethritis can cause discharge and require antibiotics. More seriously, cancer can develop in the lining of the tube. Transitional cell carcinoma is a common type of urethral cancer. Doctors may use a tool called a urethroscopy to look inside with a camera. They might also use cytology to check urine for malignant cells. Other problems include urethral strictures, which are narrowings caused by injury or stones. Kidney stones passing through the tube can also cause significant pain.