Why doesn’t stomach acid burn right through us?

It's the time of the year we think about, hmm, what am I going to do differently this year?

“Maybe I'm going to read more, maybe I'm going to work out more, maybe I'm going to learn”

a new skill but really at the top of my list is number one to get comfy and that's where Bombus comes in, they're bringing a serious comfort to all my everyday go-to's. We all new Bombus sports socks are engineered with sports specific comfort for running golf hiking skiing, snowboarding and all sport. This year I'm going to walk my dog more, longer walks, better walks and these socks

are going to help me stay comfy while I do it. And from other resolutions like going to the bookstore and picking out more books to read, I'm going to wear my new squishy Saturday-sweet slip-on shoes, which are super comfortable for being on the go.

Get over to bombus.com/family26 and use code Family26 for 20% off your first purchase.

That's BOMBAS.com/family26 code Family26 at checkout. Friends, we are so super duper excited to tell you that we just added a bunch more cities to our 2026 live show tour. We're ready for singing, dancing, magic tricks, game shows, mystery sounds, and scientists falling from the sky.

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Let me know. Brains on Universe. You're a Muslim, brains on. We're serious about being curious. Inside you, there is a squelchee churning pit of liquid.

A liquid's so dangerous, it would burn your hand if you touched it. In fact, this super-swudge can solve all kinds of things, even metal. Your body makes a lot of it every day. We're talking about stomach acid.

It's powerful and dangerous.

“So what doesn't it burn to pull right through our bodies?”

Turns out, our bodies have equally powerful defenses. We're going to learn all about it. Plus, imagine if eating rocks was good for you, for a certain animal it is. Find out which animal? Coming up.

Hi. Have you ever had this happen? I have so many questions. If only there's a podcast, then answer them. Of course, you haven't, because you have brains on.

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And my co-host today is Wesley from Columbia, Missouri. Hi, Wesley. Hi, Molly. So, Wesley, you inspired this episode with your question about stomach acid. What was that question?

“How does your stomach acid break down your food, but not hurt your stomach?”

It's such a good question. I love it so much. So, how did you come up with it? I was just sitting on the couch after I just came into my mind. Well, couches are such a good place for ideas. So, what do you think stops it from burning through us?

I think that mucus, like this stuff in your nose, stops it. Very good idea. So, what foods make your stomach happy? Would you say?

So, all the delicious foods. Is there a food that your stomach doesn't like? Most vegetables. Got it. Is there any vegetables your stomach's like?

Yeah, I could do that. I don't think so.

“So, if you're a stomach could talk, what do you think its voice would be like?”

I think its voice would be like, hey, I'm going to give me grilled cheese. I'm hungry. Straight to the point, I'm hungry. Give me your grilled cheese. I think mine's like, "Helou."

I don't know. Maybe its more like, "Helou." *whimpers* *whimpers* *whimpers*

So, today we're exploring the wonderful world inside our stomachs.

Yeah, we know our bellies are full of super powerful stomach acid.

Stomach acid is also known as gastric juice. This soup of stomach stuff is made up of a couple things. There are digestive enzymes. These are special chemicals made by our body. They help break down food.

And then there's hydrochloric acid. This is a very powerful acid, not only does it break down food, but outside of the body it can burn skin. Give it enough time, it can even dissolve some metals, like zinc. There's also water and some other things in stomach acid.

“Every day, your body makes a lot of this stuff, like three to four liters of it.”

Picture when those big party-sized balls are soda. Your body can make two of those full stomach acid every day. Like we mentioned before, it really makes you wonder. If this stomach acid is so strong, it can dissolve meat. What doesn't it dissolve us? We're basically meat too.

To get to the bottom of this belly-busting question, I asked Mark to stop by. That's right, and I'm here now. I made the perfect invention to help us get answers. Ta-da! It looks like a megaphone with a bunch of coils and blinky lights.

It's the organ of phone. It lets you phone any organ, huh? Molly, it's a device that lets you call your body parts. You just dial them up here on this keypad. And when they pick up, you can ask them questions.

I even made a jingle for it.

You never alone with the organ of phone.

You can call the spleen all ring up the heart. Grab the long-large of small intestine. It's the organ of phone. I love that jingle so much. Oh, thank you.

Can we talk to the stomach? Of course. My stomach is super chatty. Here, let's give him a call. Mark, you silly dude, what is up my guy?

I mean, besides his happiness, he's always on top of me. Yo, I swallow food. Hey, Tom, Tom. We just wanted to ask you about stomach acid. You got a sick?

Sure. I was just doing some stomach crunches, but I can hear piles on that. stomach crunches means it ups. Well, not quite.

Stemic crunches are when I notch out a bunch of crunchy things. Oh yeah. I had crispy tacos for lunch. Yeah, you did extra beefy. Just how I like it.

Me too. Billy five. That's when I slap my belly. Hey, I felt that. Right back at you, bud.

So, Mark, stomach. Tell us how you handle all that stomach acid. Of course, Mollinator. Check it out. So, when Mark is eating,

he starts by chewing up his food. Nah, nah, nah, nah, nah. That makes it all mushy and wet. Then it swallowed by the esophagus. Yo.

I'm a muscular tube. Yeah, you are, bro. When the food gets to me, that's when stomach acid starts doing its thing. So, stomach.

“Or do you start making the acid when the food is swallowed?”

Actually, stomach acid is made even before you eat. We need to be ready down here. Sometimes, just thinking about eating, like looking at a delicious plate of fiber-filled bean tacos, will get my juices flowing.

Yeah, that way the digestion party

can start the second those tasty tacos

touch down in belly town. The acid in me is strong. It helps dissolve the food into a slush. It can even kill a lot of nasty germs. There are also enzymes in the mix

that can help break down proteins and things like meats and beans. stomach. I think you're being a little modest. You also help break down food by churning it up

and squeezing it, right? Well, you know I don't like to brag, but that is my digestive dance. Squeeze and turn.

Sounds like a lot of action,

“but how come you aren't hurt by all that acid?”

No, Molly. I have my ways. And my ways. I mean, you can't. You can snooze it.

Yep. Or if I like to go it, liquid gold. A hundred percent agree. Mucous is the absolute queen. In your nose, it helps keep the air you breathe warm

and moist. It traps germs and dust and other allergy causing things. It's nature's glue trap. I'm a team Mucous all the way. Me too.

Down here in my world, Mucous is very important stuff. There are these glands in me that make a lot of Mucous.

And that Mucous acts like a shield protecting my walls

from all that nasty acid. Plus, the Mucous is full of stuff called bi-carbonate. My carbonate, that sounds familiar. Wait, isn't that baking soda? The stuff I bake with?

Good catch, Wesley. That's right. Baking soda is sodium bi-carbonate. And bi-carbonate is the bi-carbo bomb. When it comes to stopping acid,

I mean, you see, bi-carbonate is super alkaline. That means it's the opposite of acid. Correct. And when you mix acids and alkaline stuff together, they sort of can't flinch other out.

“So the Mucous has bi-carbonate that helps neutralize the acid?”

Exactly. The bi-carbonate helps stop the acid from being so... I don't know, acidity.

Plus, my other main defense is to just shed a lot of cells.

Those are the little pieces we are made of. Our bodies made up of tons and tons of cells, hair cells, eye cells, brain cells. And stomach cells? Ooh! Mine sort of sacrifice themselves constantly.

They fall off the walls of me. The stomach and that helps protect the deeper parts of my walls from getting acid blasted. Ooh! And those cells grow back pretty quick, too.

Like an armor that regenerates. In fact, the entire lining of the stomach is replaced every couple days. Wow, so the acid in the stomach is serious stuff. But the stomach has Mucous to help protect it. And the Mucous has stuff in it that helps neutralize the acid.

Also, the lining of the stomach is constantly shedding and re-growing due to the acid. Thanks for stopping by with your new invention mark. And thanks for all that info, Mark Stomach. No problem. And thanks for all you do, Stomach.

Hey, I'll keep that justing.

“If you keep feeding me extra beanie hot and cheesy tacos.”

Oh, it's my bum bum calling. I wonder what's up. Hey, Mark, Stomach. About those extra beanie tacos. Can you actually give it a rest?

I got a fart hole that stuff out eventually. And it's exhausting. I need a break. Wow, sorry dude. I didn't.

And he, just kidding, I love tuning. Keep those beans coming. And fact, now I want more. Me too. Well, that makes three of us.

Yo, I like swallowing them. Ha ha. All of me loves beans. Beans. Three hollies.

Black and pink, so we love them at the table. We love them on the go. Yo, beans. Three hollies. Pintro and black, like a song in the mouth and music in the back.

Tee-hee-hee-hee. [music playing] Wow, that was a very helpful stomach. Totally. I really learned a lot.

I hope your ears are ready to be helpful because it's time for the... [music playing] Are you ready for the mystery sound, Wesley? Yep. All right, here it is.

[music playing] Hmm. What is your guess? It sounds like someone has a fork and they're banging the fork against the pan. Totally.

That's like literally exactly what I was picturing. Let's hear it one more time. [music playing] Okay. Any new thoughts?

I still think it's that and they dropped the fork at the end. Yeah, they're like mic drop. That was a great drumming session I had and they dropped it. Okay. I'm into it.

We're going to hear it again. Get another chance to guess and hear the answer at the end of the show. Stay with us. [music playing]

Do you have a question you'd like to hear answered on the show?

Send it to us. Literally every single episode of this show comes from a question that one of our listeners have sent in to us. It is super easy. Just go to brainson.org/contact.

No question is too vague or too small.

“Did you hear something in your, like, is that really true?”

Were you hanging out in a question just like popped into your head? Do you have a thought experiment you'd like us to explore? Like if there was a lake of lemonade, would it rain lemonade?

That's a real question that we got and we answered it.

So head to brainson.org/contact and send us your question. Thank you. [music playing] Today's episode is sponsored by Bombus. It's the time of the year.

We think about, hmm, what if I got to do differently this year? Maybe I'm going to read more. Maybe I'm going to work out more. Maybe I'm going to learn a new skill but really at the top of my list is number one to get comfy. And that's where Bombus comes in.

They're bringing a serious comfort to all my everyday goto's. The all new Bombus sports socks are engineered with sports specific comfort for running golf hiking, skiing, snowboarding and all sport. This year I'm going to walk my dog more, longer walks, better walks and these socks are going to help me stay comfy while I do it. And from my other resolutions like going to the bookstore and picking out more books to read,

I'm going to wear my new squishy Saturday Swade slip-on shoes, which are super comfortable for a being on the go.

Head over to bombus.com/family26 and use code family26 for 20% off your first purchase.

That's b-o-m-b-a-s.com/family26 code family26 at checkout. You are listening to brains on, I'm Molly. And I'm Wesley. And we've learned that our stomachs are full of dangerous Bernie Melty acid. Lucky for us, they are also full of mucus that protects our stomach and they can regrow their wanting super fast when the acid damage is it?

It's a very cool system, but there are lots of other neat ways to digest food as you're about to find out. Cue the lights. Prop the questions. And give me my blazer because it's time for a game show. This game is called Digestion Suggestion. Here's how it works. I'm going to give you a suggestion for a cool way to digest food.

“And you have to guess what animal uses that mode of digestion.”

Are you ready? Yep. All right, let's go. Some people think this animal has four stomachs, but that's a myth. It has one stomach with four parts.

It likes to eat its food quickly, then go take a break and voluntarily un-swallow its food so it can chew it some more. Who's Digestion Suggestion is this? Is it A, a cow? B, a seal? C, a lion or D, a dog? I'm going to go with A, a cow. You are correct. Very good. Yes, so when an animal is chewing its food after it burps it back up, that's called chewing cod.

Hmm. All right, next question. This animal eats rocks on purpose. These little pebbles are called stomach rocks and the animal holds them in a muscular part of the stomach called the gizzard. They use these rocks to help grind down the food they swallow.

“Who's Digestion Suggestion is this? A, an ostrich? B, a giraffe?”

C, a heel monster or D, a snake. I'm going to go with a heel monster. Oh, excellent guess, but it is an ostrich. Other birds have these gizzards too, so over time the rocks wear out in the ostrich. Eat more rocks, yummy, yummy.

All right, next question. Eggs are tasty when cracked and fried, but this animal eats them shell and all. It opens wide and swallows the whole egg. Then it uses muscles to push the egg against sharp spines inside of it. That cracks the shell, so the runny, eggy goo can ooze out.

The animal swallows the goo and then throws back up the shell. Who's Digestion Suggestion is it?

See, egg eating badger or D, egg eating snake. I'm going to go with an egg eating badger.

Excellent, excellent guess, but the answer is a snake.

Surprisingly, they actually throw up the shells pretty much fully intact, which is incredible and I have no idea how that works. All right, next question. Everything about this animal is kind of you to us, but me and them. For starters, they like to eat stuff that's been dead for a while.

It doesn't really chew its food, it swallows it in chunks, and it stuffs itself with as much rotting carcass as it can. It even has a little pouch in it's throat where it can store the gross meat for future meals. Who's Digestion Suggestion is this? A, wolves. B, Wolchers. C, vampire frogs, or D, hamsters.

I'm going to go with a vulture.

And you are correct. Wolchers have extra super strong stomach acid, which pretty much kills all the germs in the rotting animal they eat.

“That's how come they don't get sick from eating it.”

Excellent, excellent work, Wesley. Thank you for playing Digestion Suggestion, muted great, and your prizes. Not having to eat like any of these animals. Enjoy not eating rocks, not throwing up eggshells, not re-chuing your food, but not eating rotting flesh.

Congratulations. Whew, that game made me the opposite of hungry, but it sure was fun. Anything in there that really surprised you? Um, I'm surprised that the cow re-eated food. Yeah, that's pretty gross, but you know, they got to do it.

They got to get all those nutrients out. So if you can have the power to digest anything in the world. Looks like something that we can't eat. What would you want to eat and why? Trying to think of something with a lot of protein.

Hmm, I like that. I'm gonna say, if I got to eat a microphone and spit it back out with the cow,

“would I just get a really loud voice for a long time?”

Ooh, I really like that, excellent answer. I'm Wesley, can you hear me now? Now let's hit pause on Digestion for a minute and see what's new in the mail room. It's time for the mail bag. Hey, oh, Santa with the mail bag.

I'm checking your letters and emails from my new favorite room in our headquarters. It's the bovine lounge. I hang out with bovine, aka cows, and I lounge about listening to my vinyl records. Like this one. Let's hear some of your ideas for new rooms to add to our headquarters.

You should add a coffee mug form to your new headquarters. You'll be able to drink hot cocoa anytime you would like. And you don't have to wash your mug because you grow them. Hi, I think we should have a manatee room that you can play with manatee's. And there's all sorts of stuff that manatee needs.

With manatee's cell, water, and digress. Hi, I have two ideas for your new HQ.

“I think that you should have a donor room, which has a half donor on the door.”

And in the inside, there's going to be lots of donor furniture.

For my second idea, I think you should have a party room.

Which has all the parties supplies you could imagine. And also I think that's in this really funny. Whoa, I also think I'm very funny. And so does Milford. She's my couch.

That's a cow that I also curl up on, like a couch. Here in the bovine lounge, all of the furniture is bovine furniture. Hmm, so cozy to cuddle a cow. Okay, well, thanks to Warren, Blake, and Francis for these ideas. We'll get right on them.

And by Wii, I mean, Molly and Mark. Because I've got more records to listen to. Cheers! Brains on is fully independent.

The best way is by joining Smartie Pass. When you do, you get access to ad revisions of all of our episodes and Smash Boom Best and forever go to help out by going to SmartiePass.org. Thank you. Welcome back.

I'm Molly here with Wesley.

Today, we've learned that our bodies make powerful acid in our stomachs

to help break down food. Right. But our stomachs protect themselves by making a ton of magical mucous. And by shutting a lot of stomach lining cells and growing new ones.

“So, how did humans figure out what's going on in the stomach anyway?”

It's not like we can peek in there. And no one has an organ of phonics at Mark. Turns out, some of the first things we learned about how the stomach works came after a serious accident. It was back in 1822, the time of horse-strong carriages. No electricity.

Handwritten letters? No cars. They had gas lamps? And some questionable ways of treating patients. As we're about to learn, our story starts with a man named Alexis St. Martin.

One day, he was shopping at a general store when he was accidentally shot. Luckily, there was a doctor nearby who could help. His name was William Beaumont. He saved Alexis's life and allowed him to live with him as he got better. Here's where things go weird.

Alexis got better, but his wound didn't heal like you would expect. Instead of the skin growing over the hole, it stayed open. That's called a fistula.

So basically, there was an opening and you could see Alexis's stomach working.

William, the doctor, thought this was super interesting. He started doing experiments with Alexis's stomach. He would tie food to a string and put it in the stomach. Part of the string was left dangling outside the opening. Then he could pull the string to take the food out.

He'd see how it changed and then he would put it back inside. He would do this over and over. It was often uncomfortable or even painful for Alexis. But William learned a lot. He wrote a whole book and it changed how we understand digestion.

The day people think what William would do was questionable. Here's why. For starters, it's not clear why he didn't try to close the wound. It's certainly would have been better for Alexis if it was closed.

“Was it impossible to fix or did William leave an open so he could do his experiments?”

Also, Alexis and the working for William. He signed contracts saying you would help with chores and stuff. Alexis got money and food and a room to sleep in. But also, the contracts said William would get to experiment on him. Again, this is questionable.

People aren't sure if Alexis really wanted to be experimented on, or if he just felt like he had to sign those contracts so he could survive. Today, scientists who want to do an experiment are supposed to explain it to a group of other scientists. And those other scientists make sure that the experiments are ethical, which means it is safe fair and known as treated badly.

Back then, we didn't have many ways to find out what was going on in the body. But today, we have scanners and cameras that can safely take pictures of our insights. That's a technology for our fantastic bodies.

Our stomachs are full of powerful acids that help break down food.

But those acids can also burn skin and even melt metal. Luckily, our stomachs make a lot of mucus that helps protect it from the acid. Our stomach lining is replaced every couple of days, so damaged parts are fixed pretty quickly. That's it for this episode of Brain Zon.

Special thanks to Jeff Martin, Kerry Martin, Mark Johnson, Ked to Borske and Quarter the North for their help with our website.

“I think it's time to go back to that mystery sound again.”

Shall we hear it? Let's do it. Alright, here it is. Do you have any new thoughts? I'm going to stick with my original answer.

So you thought it was someone banging on a pan, a metal pan with a fork, and then dropping it at the end, sort of like, yeah, I did that. Yeah, I think it's a great answer. Should we find out if you were right? I want to see.

Alright, here it is. My name is Zon Smith, and that was the sound of me flicking the tab on a soda can until it popped off. Excuse me, flicking the tab on a soda can. That's amazing. Also, so loud.

Very hard to get. So hard to get. So you were correct. There was metal going on. I guess when things are mic'd up closed, they sound so much louder than they do,

Oh, so tricky.

“I'm giving you partial credit, though, because you knew metal was happening.”

So partial credit for you. No credit for me, because I didn't even have a good guess. Well done. Way to trick us. Now it's time for the brains honor roll.

These are the incredible kids who keep the show going with their questions ideas,

“Mystery Sounds, Drawings, and High Fives.”

Andrea from Montreal, Shepherd from Pomeria, South Carolina, Boda from Atlanta, Bennett from Baltimore, Adelaide from Philadelphia, Kenna from Copper's Cove, Texas, Willow from Phoenix, Alice from Bentonville, Arkansas, Cohen from Milton Delaware, Cecilia from Honolulu, Yael from Manhattan, Nisha from Galway, Ireland,

Giuliano from San Antonio, Texas, Cora and Jude from Sup Virginia, Nora from Plano, Texas,

Arlo from Victoria, British Columbia, Talia from Chapel Hill, North Carolina, Niam

“from Salt Lake City, Naomi and Ezra from Lexington, South Carolina, Avi from Ocarber,”

Washington, Dominic from Richmond, California, Samantha from Samamish, Washington, Georgia from Columbia, Maryland, Dia, and Connor from Pennsylvania, Miles from Chapico, New York, Lena and Daphne from Southampton, Ontario,

the Lee from Clarkville, Maryland, Benjamin and Matthew from Ocarinology, Pam,

Calder and Eevee from Philadelphia, Liam from Galax, Virginia, Tesla from Oregon City, Jesse from Philadelphia, Anna from San Jose, California, Braxton from Richmond, Texas, Jesse and Ariya from Panama City, Florida, William from Washington, D.C., Jade from Holt, Summit, Missouri, Kalin from Oklahoma, June of Per from Sacramento, Kai from Fountain, Valley, California,

Calvin, Jasper, Lilly and Florence from Orm, Utah, Nathaniel from Orange, California, Rilla from Peak School, New York, Felix from G-Long, Australia, Elf from Minneapolis, Marlee from Olding and Germany, Gus from South Carolina, Jonas from Brooklyn, New York, Connor from Corpus Christi, Texas, Margo from Exeter, England, Fiona and Maisie from Yorktown Heights, New York,

Lincoln and Aurora from Pitman, New Jersey, Danielle and Kevin from Cain and Connecticut. Well, it's been from Chicago, Olivia from Maine Island, Canada, Nona from Portland, Oregon, Mira and Sorin from Charlotte and North Carolina, Edith from Anchorage, Alaska made from Tacoma, Washington and Will from Savannah, Georgia, Emma from Holles and Massachusetts, Jonathan from Golden Valley, Minnesota,

and Easy from Tampa, Florida. We'll be back next week with an episode all about different generations. Thanks for listening.