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Chloe Effron/iStock

Why Does My Stomach Rumble When I’m Hungry?

Chloe Effron/iStock
Chloe Effron/iStock

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

A gurgling, rumbling stomach doesn’t always mean that you’re hungry. It just means your digestive (die-JES-tiv) system is trying to do its job, moving food through your body and getting the nutrients (NEW-tree-ents) that give you energy and help you grow. As your body absorbs these nutrients and gets rid of food waste, though, your stomach empties out and often seems to get noisier!

Your gastrointestinal (gas-tro-in-TES-tin-uhl) tract plays a big role in moving food through your body. It’s a kind of long tube that runs from your mouth (where the food goes in) to your anus (where the poop comes out). Along the way, the food passes through your stomach. A rumbling tummy means the muscles in your stomach and small intestines are squeezing together to push food, liquids, and gases through your gastrointestinal tract. That rumbling gets a lot louder when your stomach is mostly empty.

When the muscles in your stomach and small intestines are pushing everything along after a big meal, all the food packed inside muffles the sound. But if it’s been a while since you’ve eaten, most of that food is gone. Instead, your stomach and intestines contain mostly air and only a little liquid and food. So when the muscles of the stomach and small intestines squeeze, those gurgling gases and liquids inside your empty stomach are easier to hear. 

Watch this D News video of a doctor using a plastic bag, a tube, and some water to demonstrate (or show) how an empty stomach makes noise.  

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iStock/Chloe Effron
Why Do I Get Cavities?
iStock/Chloe Effron
iStock/Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Your mouth is a busy place. There are hundreds of different kinds of bacteria living on your teeth, tongue and gums. Bacteria, as you may know, are tiny little critters that can only be seen with a microscope. We need some of them to help keep us healthy. Others are more of a pain—especially when they cause cavities (CAA-vih-teez), or little holes in our teeth. If you get a cavity, a dentist will have to treat it. You may get a filling.

During the day, you put all kinds of food into your mouth. When you eat, the bacteria that live in there eat, too. Some bacteria make acid out of the sugar in food. So when you eat sweet stuff—candy, cookies, and sugary drinks—you are helping bacteria to make more acid. The acid eats through the enamel, or the hard coating on your teeth. Over time, this can cause cavities and infections. Ouch! Luckily your spit, or saliva (suh-LIE-vuh), has minerals in it, like calcium and phosphate, that fight back by making your tooth enamel stronger and cutting down on acid. The fluoride in toothpaste helps do this, too. If you have a cavity, a dentist can fill the hole to keep bacteria from getting in and causing a bad infection. Unfortunately, there’s another reason for cavities that you don’t control: genes (jeenz).

Genes are little codes inside our cells that get passed down from our parents. They are instructions to our bodies that affect how we look, act, and grow. Genes may play a big part in whether we get cavities. Some people end up with cavities because of their genes, even if they take really good care of their teeth. Other people hardly get any. We can’t change our genes, but we can control other things. Brushing your teeth, visiting the dentist, and avoiding sweets can all help you keep cavities away.

Want to find out more about what lives inside your mouth? Watch the cartoon below from the National Institutes of Health.

 

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iStock/Chloe Effron
Why Do Lizards Lose Their Tails and Regrow New Ones?
iStock/Chloe Effron
iStock/Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Many species of lizard lose their tails when they are being chased. When a predator (PREH-duh-tor)—an animal that wants to eat them, like a bird or cat—grabs for the tail, it falls off, and the lizard can run away. How does it happen? Scientists looking at geckos (a type of lizard) under a microscope have found out that some parts of the tail are weaker than other parts.

It’s no accident. The sections of a lizard’s tail will hold together until the lizard is in danger. Scientists think that’s when special cells inside the tail make chemicals that attack the weak points. Then—surprise!—the tail breaks off. It will also keep wiggling for a while to distract the predator while the lizard speeds off. Pretty awesome! That’s not the end of the story, either. Most lizard species can also grow a new tail. 

Lizard tails have a lot of jobs to do. Lizards move their tails around to “talk” to each other. It’s a kind of secret lizard language. The tail also helps lizards keep their balance when they’re scrambling up a tree or jumping from rock to rock. So even though losing the tail is a useful trick, growing it back is pretty important, too. Sometimes lizards can get carried away, though: one busy lizard from Argentina grew six new tails at once!

Watch a gecko regrow its tail in this video

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