What is the urinary system?

The urinary system works as a filter, removing toxins and wastes from your body through urine. It uses a series of tubes and ducts to pass this waste. These tubes are connected to your blood vessels and digestive system. Your urinary system helps the rest of your body work properly.

What does the urinary system do?

Your urinary system filters your blood to get rid of what your body doesn’t need. It eliminates extra water and salt, toxins, and other waste products. Different parts of the urinary system perform tasks including:

  • Filtering blood.
  • Separating the toxins you don’t need from the nutrients you do need.
  • Storing and carrying urine out of your body.

What are the parts of the urinary system?

The kidneys, ureters, bladder and urethra make up the urinary system. They all work together to filter, store and remove liquid waste from your body. Here’s what each organ does:

  • Kidneys: These organs work constantly. They filter your blood and make urine, which your body eliminates. You have two kidneys, one on either side of the back of your abdomen, just below your rib cage. Each kidney is about as big as your fist.
  • Ureters: These two thin tubes inside your pelvis carry urine from your kidneys to your bladder.
  • Bladder: Your bladder holds urine until you’re ready to empty it (pee). It’s hollow, made of muscle, and shaped like a balloon. Your bladder expands as it fills up. Most bladders can hold up to 2 cups of urine.
  • Urethra: This tube carries urine from your bladder out of your body. It ends in an opening to the outside of your body in the penis (in males) or in front of the vagina (in females).

How does the urinary system clean my blood?

Your kidneys are an essential part of filtering your blood. Here’s how the urinary system works:

  1. Your blood enters each kidney through lots of little arteries.
  2. Your kidneys filter your blood, separating toxins from nutrients.
  3. Vitamins, minerals, nutrients and proteins return to your bloodstream.
  4. Waste products and urine move through your ureters to your bladder. Your bladder stores urine until you use the toilet.
  5. Urine leaves your body through your urethra.

What conditions and disorders affect the urinary system?

Many conditions can affect the ureters, kidneys, bladder and urethra. Infections, diseases, or problems can appear at birth or develop as you get older. Some common urinary disorders are:

  • Infections: Urinary tract infections and sexually transmitted infections (STIs) can cause issues in the kidneys, urethra, or bladder. These infections occur when bacteria or viruses enter the urinary tract through the urethra. Your doctor can prescribe medication to treat an infection.
  • Structural problems: Sometimes babies are born with birth defects that affect the way the urinary tract is formed. These abnormalities can cause urine to back up in the kidneys and cause infection. Later in life, a bladder prolapse can occur after pregnancy or as women age. A prolapsed bladder drops into the vagina or hangs out of the vaginal opening. Sometimes structural issues need surgery to repair them.
  • Kidney stones: These masses form when waste products in urine clump together. Kidney stones or ureteral stones (kidney stones that move to the ureter) can cause severe pain and block the flow of urine. Your doctor may use ultrasound (sound waves) to break the stones into tiny pieces so they’re easier to pass.
  • Urination problems: Loss of bladder control, or urinary incontinence (leakage), causes urine to leak a little or a lot. Urinary incontinence most often occurs in women, usually after pregnancy or later in life. It can be worse when you cough, laugh, sneeze or jump. Overactive bladder happens when you feel the sudden urge to urinate often. Medications can help treat these conditions.
  • Urinary tract obstruction: Growths or cancerous tumors in the abdomen can affect the flow of urine. In men, an enlarged prostate (also called benign prostatic hyperplasia or BPH) can block the ureter so it’s harder to urinate. BPH can be treated with medications or surgery. Other causes of ureteral obstruction include pregnancy and gastrointestinal (GI) issues like Crohn’s disease.
  • Kidney disease: The most common causes of chronic kidney disease are high blood pressure and diabetes. Controlling blood pressure and blood sugar is crucial to lowering your risk of kidney disease. A genetic condition called polycystic kidney disease causes fluid-filled cysts to form inside the kidneys. Non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil®) or naproxen (Aleve®), may damage the kidneys. The usual recommended dose of acetaminophen (Tylenol®) is safe for your kidneys. Check with your doctor to learn which over-the-counter pain medicines are safest for you. Overdoses of almost all medicines—prescription and over-the-counter—can cause the kidneys to work too hard when filtering waste, which can lead to kidney failure. Kidney failure may require dialysis or a kidney transplant.
  • Interstitial cystitis: Also called painful bladder syndrome, this condition causes inflammation (swelling and irritation) in the bladder. Medications and physical therapy can improve the symptoms of painful bladder syndrome.

How common are these conditions?

The most common urinary issues are bladder infections and urinary tract infections (UTIs). UTIs are more common in women than in men. More than 60% of women will get a UTI in their lifetime.

About half of women over 65 experience urinary incontinence, usually because of stretched muscles from pregnancy and childbirth. Kidney stones are also fairly common, occurring in about 1 in every 10 people.

How can I keep my urinary system healthy?

You can’t prevent most urinary tract problems. But you can try to keep your urinary system healthy with proper hygiene and a healthy lifestyle. To help your urinary system work the way it should, you can:

  • Drink plenty of water: Staying hydrated will flush out your system and can help you prevent kidney stones and UTIs. You can try drinking cranberry juice to ward off a UTI. Compounds in cranberries may stop bacteria from growing.
  • Eat a healthy diet: Low sodium, high-calcium foods may prevent kidney stones.
  • Wipe the right way: Women should always wipe front to back after using the toilet. Proper wiping reduces the risk of bacteria getting into the vagina and causing a UTI.
  • Empty your bladder after sex: If you’re a woman, you should use the bathroom after having sex. Peeing promptly can clear out bacteria and reduce your risk of a UTI.
  • Practice safe sex: Protect yourself from an STI with a condom. But be careful with spermicides because they can cause bacteria to flourish.
  • Do pelvic floor exercises: Also called Kegel exercises, these can reduce your risk of urinary incontinence by strengthening the muscles in your pelvic floor.

When should I call my doctor if I think I might have a problem with my urinary tract?

If you’re having trouble or pain when urinating, you should visit your doctor. It may be a sign of an infection or another condition. Call your doctor if you have:

  • Blood in your urine.
  • Burning sensation, pain or difficulty urinating.
  • Pain in your pelvic area, lower back, genital area, or flank (the back and sides of your abdomen).
  • Trouble holding your urine or problems with leaking urine.
  • A feeling that something is bulging out of your vagina.
  • Urgent need to urinate or the need to urinate often, especially if it’s worse at night.
  • Swollen feet or legs.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy