What does your urinary system do?
Huh? Are you asking yourself what's a system, anyway?

A body system is a set of body parts that do a particular job. In this case, it's filtering out excess fluid and other substances from your bloodstream. Some fluid gets reabsorbed by your body but most gets expelled as urine. If your body weren't clever enough to get rid of some of this stuff, you'd get sick!

How does the urinary system work?
Your body makes chemical waste products it can't use. They go into your bloodstream, then pass into your kidneys where the excess fluid and chemical stuff your body can't use is filtered out.

As your kidneys do this work, they also make sure that your blood is just the right combination -- not too thin or too thick, not too salty, or overloaded with excess vitamins and minerals or wastes made by other parts of the body.

The kidneys work as they do because they contain millions of infinitesimal filters. Hundreds of times a day the blood in your body gets filtered through these filters and the liquid and wastes are removed. The wastes trickle down and collect in the center of your kidneys. Your kidneys are always working and the pee is always drip--drip--dripping down through tubes called the ureters into a stretchy pouch. This stretchy pouch is your bladder and it can stretch enough to hold a pint of urine!

When your bladder becomes too full, it sends a message to your brain. You feel the need to pee and start looking for a place to do it. When the time and place are right, your brain orders the muscles around your bladder to start squeezing and for the circle of muscles at the bottom of your bladder to open. Pee squirts out through the urethral opening in your body. Hopefully, the pee meets the water of a toilet. Now that spells relief!