Nasal mucosa
Courtesy of NIH
Nasal mucus is very important to our health – and actually kind of magical. There’s a lot going on in our noses all the time that we don’t appreciate. Where do boogers come from? Why does your nose run when you’re out in the cold? Why does your nose get stuffy when you’re sick?
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[MUSIC PLAYING] MOLLY BLOOM: You're listening to Brains On from NPR News and Southern California Public Radio. We're serious about being curious. I'm Molly Bloom and I am really excited about today's topic. Too excited, maybe? No, no, I am really excited because your questions led me to find out that nasal mucus is really, really cool, kind of, magical even.
Now, I know our last episode was about farts and it might seem too soon to explore boogers, but part of the reason that these two are back to back is that we're getting ready for a live show in November called Gross Out. At the show, we'll be discussing the science of blood, boogers, and farts. The show is in Saint Paul, Minnesota, and if you want to find out more, you can head to fitzgeraldtheater.org. And if you do buy tickets, you can use the promo code brains to get $5 off per ticket.
So to get ready for that show, we're answering the questions that you've sent us about what's inside our noses. As it turns out, boogers are just the tip of the iceberg or booger bug. OK, I'm sorry for that. But our first question today comes courtesy of Harrison in Lakewood Ranch, Florida.
SUBJECT 1: My question is, how do boogers get in your nose and why aren't they in other parts of your body?
MOLLY BLOOM: Awesome, Harrison, a two part question. First, the source. Boogers come from mucus that's made in our noses and it's basically super powered. Dr. Holly Boyer, who is an otolaryngologist at the University of Minnesota, treats patients who have nasal and sinus issues.
HOLLY BOYER: I have a lot of experience with nasal mucus.
MOLLY BLOOM: And it's really important stuff. That mucus does some key things for our bodies. First, it makes sure the air we breathe in doesn't hurt our lungs.
HOLLY BOYER: It moisturizes the air that you breathe. If you go outside and it's cold and you're breathe in through your mouth, it hurts your throat. It hurts your lung. It kind of burns. But if you breathe through your nose, the air becomes completely humidified. By the time it reaches the back of the nose, it's almost 100% humidified. So the air that reaches your lungs is nice and wet and it doesn't hurt your lungs.
MOLLY BLOOM: The other thing mucus does is it cleans and filters the air that we breathe and the way it does that is super cool. Our noses are constantly making mucus. It's made by what are called goblet cells.
HOLLY BOYER: The mucus in your nose is a sticky substance it's made partially of water, actually mostly water, about 95% water, more specifically, it's saltwater and about 5% of is made of sticky substances like proteins and substances that your body secretes to make it sticky.
MOLLY BLOOM: And that stickiness is key. It acts as a kind of flypaper that traps nasty things that we don't want to breathe into our lungs.
HOLLY BOYER: Viruses, fungus, bacteria, dust, pollens. There are chemicals in there that make it really hostile for bacteria, and fungi, and viruses to live. So there are chemicals and cells that attack those invaders. There's also antibodies to recognize whether or not it's something good or something bad.
MOLLY BLOOM: So once these get caught, where do they go? It turns out your nose is an efficient, self-cleaning system basically replacing your nasal mucus every 20 minutes.
HOLLY BOYER: So the same cells that line the inside of the nose that secrete the mucus also have little tiny microscopic hairs on them. And it's really interesting that the flow of mucus is preprogrammed. It constantly is being swept into the back of the nose, except for very small part in the front of your nose which gets propelled forward, which is in a very convenient place for your fingers to reach it.
MOLLY BLOOM: These hairs Holly mentioned aren't the ones you can see at the front of your nose. Those are great for filtering out big things like bugs and dirt. The hairs that sweep the mucus back and out of your nose are very, very tiny.
HOLLY BOYER: You can only see these with a microscope and they're constantly moving. So that sticky mucus that's full of all that bad stuff that it filtered out of the air, you swallow that, and it's fine to swallow. An interesting fact is that your nose produces 1 to 2 liters of mucus per day.
And most of that, you don't even notice because it's continually being swept into the back of your nose by those little hairs and you just swallow it. A good thing about swallowing is that when it goes into your stomach, anything that's alive, like a virus, or bacteria, or fungus, dies because of the acid content in your stomach. So the acid in your stomach kills all that stuff that your nose so efficiently filtered.
MOLLY BLOOM: So it's pretty sophisticated. The air you breathe in through your nose goes to your lungs. But the mucus produced by your nose goes into your stomach. Now, like Holly said, most of the mucus is swept back and swallowed but a small bit at the front is pushed forward where it becomes boogers. OK, now for the second part of Harrison's question.
SUBJECT 1: How do boogers get in your nose and why aren't they in other parts of your body?
HOLLY BOYER: That's a really good question but there is a logical answer to that. So there are other places in your body where you make mucus. You make mucus in your stomach, and in your GI tract, and in your lungs. Your nose, however, is where all of the air in the atmosphere comes into your body so it dries out. So boogers are just dry mucus and it's just airflow.
MOLLY BLOOM: Very logical indeed. Dr. Holly Boyer is going to be back with more booger science in just a minute. But first, the mystery sound. Here it is. Any guesses? We'll be back with the answer in just a bit.
[MUSIC PLAYING]
Any questions you want to hear answered on Brains On, any mystery sounds you want to share, or maybe you just want to send us a drawing or a high five? You can email us any time at brainson@m-- as in Minnesota-- pr.org. You can also send us actual letters in the actual mail. You can find our mailing address at our website, brainson.org, and while you're there, you can sign up for our newsletter.
That's where we've been recommending other cool podcasts and websites for you to check out, letting you know about new episodes and events, plus soon will be doing contests and fun quizzes through the mailing list too. Make sure you don't miss any of it by signing off. Now, it's time for the brains honor roll. These are the awesome kids who keep the show going with their ideas, mystery sounds, and high fives. Here's the most recent group of kids to be added to the brains honor roll.
[LISTING HONOR ROLL]
All right, back to the mystery sound. Let's hear it again. Any guesses? Here's a hint. This device can be illuminating. Any new ideas? Let's hear it one more time. Here with the answer is 8-year-old Jane from California.
SUBJECT 2: That was the sound of my lamp turning on and off. I picked that sound because it makes a good loud noise and I like that.
MOLLY BLOOM: Thanks, Jane. Now, back to your bigger questions. Next up is Milo from West Palm Beach, Florida.
SUBJECT 3: My question is, why does your nose get stuffy when you're sick?
MOLLY BLOOM: Good question, Milo. I mean, you'd think our bodies would try to help us breathe by giving us as much air as possible, not trying to make it harder to breathe. Here's Dr. Holly Boyer with the answer.
HOLLY BOYER: So when you get sick, especially with viral infections, the most common infection in the nose, the virus goes in and it infects that lining tissue to the nose and all of those cells that are producing mucus and that have those little hairs, those get damaged.
And when they're damaged, there's irritation of the underlying tissue and one of the responses that your body has is to secrete lots of mucus. Part of that is probably to try to wash the debris out of the nose and that's why you have thicker mucus. It's more colored when you have an infection, is that it's full of debris and dead cells. So that increased amount, it may be somewhat protective in that it's trying to wash some of that away. And it also promotes healing because for the inside of your nose to heal after viral infection, it's almost like healing from a burn, the inside needs to be healthy and moist to promote that healing
MOLLY BLOOM: Our next and last question is from Lydia of Holland, Michigan.
SUBJECT 4: Why do you get a runny nose when you're outside in the cold, shouldn't your snot freeze?
MOLLY BLOOM: Great question. Not only is our nose able to humidify the air we breathe, it's also an excellent thermometer.
HOLLY BOYER: So there's a really sensitive temperature sensing system in the nose. And when you breathe in cold air, it increases the blood flow to your nose because your nose is really efficient at also warming the air. So, like I said before, when you breathe in cold, dry air, it hurts your lungs. The coldness hurts your lungs too, so the increased blood flow to the nose warms the air that you breathe. As you increase the blood flow, you also increase some of the stimulation to the nose that produces secretions.
MOLLY BLOOM: So more blood in the nose means more mucus produced by those cells and it's warm enough inside your nose that it doesn't freeze. So our noses and the mucus that's in them is pretty amazing and important. Dr. Holly Boyer hopes you give a little love to the super powered nasal mucus that keeps us healthy.
HOLLY BOYER: Mucus is good for you. It's protecting your lungs. It's filtering out things that could hurt you. And even though people think it's annoying and gross, if you didn't have it, you'd have a lot more trouble.
- So maybe next time you blow your nose, say thanks to all that mucus before you toss it out. That's it for this episode of Brains On. We'll be back very soon with more answers to your questions. In the meantime, you can find us on Instagram and Twitter @brains_on and we're on Facebook too. You can also sign up for our newsletter by heading to our website brainson.org. Thanks for listening.
[MUSIC PLAYING]
Now, I know our last episode was about farts and it might seem too soon to explore boogers, but part of the reason that these two are back to back is that we're getting ready for a live show in November called Gross Out. At the show, we'll be discussing the science of blood, boogers, and farts. The show is in Saint Paul, Minnesota, and if you want to find out more, you can head to fitzgeraldtheater.org. And if you do buy tickets, you can use the promo code brains to get $5 off per ticket.
So to get ready for that show, we're answering the questions that you've sent us about what's inside our noses. As it turns out, boogers are just the tip of the iceberg or booger bug. OK, I'm sorry for that. But our first question today comes courtesy of Harrison in Lakewood Ranch, Florida.
SUBJECT 1: My question is, how do boogers get in your nose and why aren't they in other parts of your body?
MOLLY BLOOM: Awesome, Harrison, a two part question. First, the source. Boogers come from mucus that's made in our noses and it's basically super powered. Dr. Holly Boyer, who is an otolaryngologist at the University of Minnesota, treats patients who have nasal and sinus issues.
HOLLY BOYER: I have a lot of experience with nasal mucus.
MOLLY BLOOM: And it's really important stuff. That mucus does some key things for our bodies. First, it makes sure the air we breathe in doesn't hurt our lungs.
HOLLY BOYER: It moisturizes the air that you breathe. If you go outside and it's cold and you're breathe in through your mouth, it hurts your throat. It hurts your lung. It kind of burns. But if you breathe through your nose, the air becomes completely humidified. By the time it reaches the back of the nose, it's almost 100% humidified. So the air that reaches your lungs is nice and wet and it doesn't hurt your lungs.
MOLLY BLOOM: The other thing mucus does is it cleans and filters the air that we breathe and the way it does that is super cool. Our noses are constantly making mucus. It's made by what are called goblet cells.
HOLLY BOYER: The mucus in your nose is a sticky substance it's made partially of water, actually mostly water, about 95% water, more specifically, it's saltwater and about 5% of is made of sticky substances like proteins and substances that your body secretes to make it sticky.
MOLLY BLOOM: And that stickiness is key. It acts as a kind of flypaper that traps nasty things that we don't want to breathe into our lungs.
HOLLY BOYER: Viruses, fungus, bacteria, dust, pollens. There are chemicals in there that make it really hostile for bacteria, and fungi, and viruses to live. So there are chemicals and cells that attack those invaders. There's also antibodies to recognize whether or not it's something good or something bad.
MOLLY BLOOM: So once these get caught, where do they go? It turns out your nose is an efficient, self-cleaning system basically replacing your nasal mucus every 20 minutes.
HOLLY BOYER: So the same cells that line the inside of the nose that secrete the mucus also have little tiny microscopic hairs on them. And it's really interesting that the flow of mucus is preprogrammed. It constantly is being swept into the back of the nose, except for very small part in the front of your nose which gets propelled forward, which is in a very convenient place for your fingers to reach it.
MOLLY BLOOM: These hairs Holly mentioned aren't the ones you can see at the front of your nose. Those are great for filtering out big things like bugs and dirt. The hairs that sweep the mucus back and out of your nose are very, very tiny.
HOLLY BOYER: You can only see these with a microscope and they're constantly moving. So that sticky mucus that's full of all that bad stuff that it filtered out of the air, you swallow that, and it's fine to swallow. An interesting fact is that your nose produces 1 to 2 liters of mucus per day.
And most of that, you don't even notice because it's continually being swept into the back of your nose by those little hairs and you just swallow it. A good thing about swallowing is that when it goes into your stomach, anything that's alive, like a virus, or bacteria, or fungus, dies because of the acid content in your stomach. So the acid in your stomach kills all that stuff that your nose so efficiently filtered.
MOLLY BLOOM: So it's pretty sophisticated. The air you breathe in through your nose goes to your lungs. But the mucus produced by your nose goes into your stomach. Now, like Holly said, most of the mucus is swept back and swallowed but a small bit at the front is pushed forward where it becomes boogers. OK, now for the second part of Harrison's question.
SUBJECT 1: How do boogers get in your nose and why aren't they in other parts of your body?
HOLLY BOYER: That's a really good question but there is a logical answer to that. So there are other places in your body where you make mucus. You make mucus in your stomach, and in your GI tract, and in your lungs. Your nose, however, is where all of the air in the atmosphere comes into your body so it dries out. So boogers are just dry mucus and it's just airflow.
MOLLY BLOOM: Very logical indeed. Dr. Holly Boyer is going to be back with more booger science in just a minute. But first, the mystery sound. Here it is. Any guesses? We'll be back with the answer in just a bit.
[MUSIC PLAYING]
Any questions you want to hear answered on Brains On, any mystery sounds you want to share, or maybe you just want to send us a drawing or a high five? You can email us any time at brainson@m-- as in Minnesota-- pr.org. You can also send us actual letters in the actual mail. You can find our mailing address at our website, brainson.org, and while you're there, you can sign up for our newsletter.
That's where we've been recommending other cool podcasts and websites for you to check out, letting you know about new episodes and events, plus soon will be doing contests and fun quizzes through the mailing list too. Make sure you don't miss any of it by signing off. Now, it's time for the brains honor roll. These are the awesome kids who keep the show going with their ideas, mystery sounds, and high fives. Here's the most recent group of kids to be added to the brains honor roll.
[LISTING HONOR ROLL]
All right, back to the mystery sound. Let's hear it again. Any guesses? Here's a hint. This device can be illuminating. Any new ideas? Let's hear it one more time. Here with the answer is 8-year-old Jane from California.
SUBJECT 2: That was the sound of my lamp turning on and off. I picked that sound because it makes a good loud noise and I like that.
MOLLY BLOOM: Thanks, Jane. Now, back to your bigger questions. Next up is Milo from West Palm Beach, Florida.
SUBJECT 3: My question is, why does your nose get stuffy when you're sick?
MOLLY BLOOM: Good question, Milo. I mean, you'd think our bodies would try to help us breathe by giving us as much air as possible, not trying to make it harder to breathe. Here's Dr. Holly Boyer with the answer.
HOLLY BOYER: So when you get sick, especially with viral infections, the most common infection in the nose, the virus goes in and it infects that lining tissue to the nose and all of those cells that are producing mucus and that have those little hairs, those get damaged.
And when they're damaged, there's irritation of the underlying tissue and one of the responses that your body has is to secrete lots of mucus. Part of that is probably to try to wash the debris out of the nose and that's why you have thicker mucus. It's more colored when you have an infection, is that it's full of debris and dead cells. So that increased amount, it may be somewhat protective in that it's trying to wash some of that away. And it also promotes healing because for the inside of your nose to heal after viral infection, it's almost like healing from a burn, the inside needs to be healthy and moist to promote that healing
MOLLY BLOOM: Our next and last question is from Lydia of Holland, Michigan.
SUBJECT 4: Why do you get a runny nose when you're outside in the cold, shouldn't your snot freeze?
MOLLY BLOOM: Great question. Not only is our nose able to humidify the air we breathe, it's also an excellent thermometer.
HOLLY BOYER: So there's a really sensitive temperature sensing system in the nose. And when you breathe in cold air, it increases the blood flow to your nose because your nose is really efficient at also warming the air. So, like I said before, when you breathe in cold, dry air, it hurts your lungs. The coldness hurts your lungs too, so the increased blood flow to the nose warms the air that you breathe. As you increase the blood flow, you also increase some of the stimulation to the nose that produces secretions.
MOLLY BLOOM: So more blood in the nose means more mucus produced by those cells and it's warm enough inside your nose that it doesn't freeze. So our noses and the mucus that's in them is pretty amazing and important. Dr. Holly Boyer hopes you give a little love to the super powered nasal mucus that keeps us healthy.
HOLLY BOYER: Mucus is good for you. It's protecting your lungs. It's filtering out things that could hurt you. And even though people think it's annoying and gross, if you didn't have it, you'd have a lot more trouble.
- So maybe next time you blow your nose, say thanks to all that mucus before you toss it out. That's it for this episode of Brains On. We'll be back very soon with more answers to your questions. In the meantime, you can find us on Instagram and Twitter @brains_on and we're on Facebook too. You can also sign up for our newsletter by heading to our website brainson.org. Thanks for listening.
[MUSIC PLAYING]
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