Today’s Wonder of the Day was inspired by Calvin. Calvin Wonders, “How do medicines know where to go in the body?” Thanks for WONDERing with us, Calvin!

Ouch! That hurts! Whether it's a headache, an earache, sore shins from the soccer field, or a fall on the playground, we all feel pain from time to time.

Pain isn't fun. In fact, it can disrupt our lives. Until it goes away, it can be…well…a real pain to deal with!

If you feel pain, you should tell your parents or an adult. Fortunately, there are many medicines — called pain relievers — that can help you feel better right away.

The two most common pain relievers used by kids are called acetaminophen and ibuprofen. These medicines may go by brand names, like Tylenol® and Advil®.

When you swallow a pain reliever (either as a liquid or a pill), do you have to tell it to go to your head, your ear, or your shin? Nope!

The medicine in a pain reliever doesn't go directly to whatever part of your body is hurting. Instead, pain relievers work by going everywhere.

After you swallow a pain reliever, it goes to your stomach where it's digested and absorbed into your bloodstream. Once it gets in your blood, the medicine travels throughout your whole body.

So how does this help that one spot where you're hurting feel better?

When cells in your body become injured or damaged, they release a chemical called prostaglandin. Your body's nerve endings are very sensitive to prostaglandin.

When they sense a release of prostaglandin, your nerve endings transmit a message through the nervous system to your brain, telling it where and how much an area of the body hurts. Pain relievers work — all throughout the body — by preventing injured cells from releasing prostaglandin.

When cells stop releasing prostaglandin, the nervous system stops sending pain messages to the brain. When the brain stops receiving pain messages, you stop feeling pain.

But pain isn't always bad, even if it doesn't feel very good. Pain is your body's way of warning you that something is wrong so you can fix it.

If you didn't feel pain, you might not realize that there was a problem, and it could get much worse before you notice it on your own.

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