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Children's Hospital of Orange County
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Your Urinary System

What's the Urinary System (Urinary Tract)?

The urinary system (also called the urinary tract) is one of the systems our bodies use to get rid of waste products. The kidneys are the part of the urinary tract that makes urine (pee). Urine has salts, toxins, and water that need to be filtered out of the blood. After the kidneys make urine, it leaves the body using the rest of the urinary tract as a pathway.

What Are the Parts of the Urinary System (Urinary Tract)?

You drink, you pee. But urine is more than just that drink you had a few hours ago. The body produces pee as a way to get rid of waste and extra water that it doesn't need. Before leaving your body, urine travels through the urinary tract.

The urinary tract is a pathway that includes the:

  • kidneys: two bean-shaped organs that filter waste from the blood and produce urine
  • ureters: two thin tubes that take pee from the kidney to the bladder
  • bladder: a sac that holds pee until it's time to go to the bathroom
  • urethra: the tube that carries urine from the bladder out of the body when you pee
  • How the Urinary System Works

    How the Urinary System Works

    Watch this movie about the urinary system, which makes pee.

What Do the Kidneys Do?

The kidneys are key players in the urinary tract. They do two important jobs:

  • filter waste from the blood, and
  • produce pee (urine)  to get rid of it

If the kidneys didn't do this, toxins (bad stuff) would quickly build up in your body and make you sick. That's why you hear about people getting kidney transplants sometimes. You need at least one working kidney to be healthy.

The kidneys are under the ribcage in the back, one on each side. Each adult kidney is about the size of a fist.

You might wonder how your body ends up with waste it needs to get rid of. Body processes such as digestion and metabolism (when the body turns food into energy) produce wastes, or byproducts. The body takes what it needs, but the waste has to go somewhere. Thanks to the kidneys and pee, it has a way to get out.

What Are the Ureters? 

Pee travels out of the kidneys through the ureters (pronounced: YUR-uh-ters) to be stored in the bladder (a muscular sac in the lower belly).

What Does the Bladder Do?

Once pee is produced, it travels from the kidney to the bladder, where it's stored until you need to go to the bathroom. The bladder expands as it fills; when it's full, nerve endings in the bladder wall send a message to the brain that you need to pee.

When you're in the bathroom, ready to go, the bladder walls contract and the sphincter (a ringlike muscle that guards the exit from the bladder to the urethra) relaxes. The urine then flows from the bladder and out of the body through the urethra. 

What's the Urethra?

When a person urinates, the pee exits the bladder and goes out of the body through the urethra (pronounced: yoo-REE-thruh), another tube-like structure. The male urethra ends at the tip of the penis; the female urethra ends just above the vaginal opening.

What's Pee (Urine)?

Let's talk more about how the kidneys filter blood. When blood goes through the kidneys, water and some of the other stuff that is in blood (like protein, glucose, and other nutrients) go back into the bloodstream, while the waste and excess stuff is taken out. Urine is what is left behind. But what is it exactly?

Urine contains:

  • water
  • urea, a waste product that forms when proteins are broken down
  • urochrome, a pigmented blood product that gives urine its yellowish color
  • salts
  • creatinine, a waste product that forms with the normal breakdown of muscle
  • byproducts of bile from the liver
  • ammonia

When you're asked to give a urine sample during a doctor's visit, the results reveal how well your two kidneys are working. For example, white blood cells in the urine can be a sign of an infection.

Pee also is a way for your body to keep the right amount of water. Did you ever notice that if you drink a lot, you pee more and the pee is pale yellow? That's because your body is getting rid of extra water and your pee has more water in it than usual.

 

How Can I Keep My Urinary System (Urinary Tract) Healthy?

You might not think much about peeing or your urinary tract, but here's how you can help keep everything flowing as it should:

  • Drink enough fluids. There's no magic amount, but be sure to drink plenty of water, especially when it's warm out or you're exercising and playing.
  • For girls: Wipe from front to back, especially after going poop. Because of where the urethra is for girls, it's easy for bacteria from poop to get in that area. If some of those bacteria end up in the urinary tract, you could get an infection known as a UTI (urinary tract infection).
  • For everyone: Go to the bathroom when you need to go. Holding too long isn't good for your urinary tract — and it can lead to accidents. Uh-oh!
Reviewed by: KidsHealth Medical Experts
Date reviewed: January 2023