A stretchy storage bag
Your bladder sits low in your belly, inside the bowl of your hip bones.
It's hollow and made of stretchy muscle. When it's empty, it's small and wrinkly, like a balloon with no air. As it fills with pee, it stretches and gets rounder.
A grown-up's bladder can hold about 2 cups of pee. Kids' bladders are smaller, and they grow as you grow.
The pee pathway
Pee starts in your kidneys. Two thin tubes called ureters carry it down to your bladder, a little at a time, all day long.
When you go to the bathroom, pee leaves the bladder through another tube, the urethra (yoo-REE-thruh), and goes out of your body.
So the trip goes: kidneys, ureters, bladder, urethra, and out!
Your bladder talks to your brain
The walls of your bladder have stretch sensors. As it fills, they send messages to your brain: getting full!
Your brain lets you choose when to go. A ring of muscle, like a drawstring, stays closed until you're ready and let it relax.
Babies can't control this yet, which is why they wear diapers. Learning to listen to your bladder takes practice, and every kid learns at their own pace.
Don't hold it too long
It's fine to wait a little while, but try not to hold your pee for a very long time. When you feel the urge, go.
Holding it too long, again and again, can make it easier for germs to grow in your bladder.
When you go, take your time and let it all out. Then wash your hands.