Episode

Episode | Quick Take

Kevin Patton tackles one of A&P’s slimiest subjects: mucus. In this playful but powerful episode, he reveals ten (or eleven) reasons mucus deserves more attention in our teaching. From immunity to fertility, mucus does it all.

00:00 | Introduction

00:45 | Mucus & Mucous

04:27 | Virtual HAPS Conference *

05:41 | Mucus: Body-Wide Protector

10:13 | Gross Episodes *

11:15 | Mucus in Motion

15:46 | Kerry Hull Honored *

16:28 | Mucus & the Human Story

20:42 | Running Concept Lists

21:11 | Mucus is Vital

26:05 | Staying Connected

* Breaks

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Episode | Transcript

The A&P Professor podcast (TAPP radio) episodes are made for listening, not reading. This transcript is provided for your convenience, but hey, it’s just not possible to capture the emphasis and dramatic delivery of the audio version. Or the cool theme music.  Or laughs and snorts. And because it’s generated by a combo of AI robot and human transcription, it may not be exactly right. So I strongly recommend listening by clicking the audio player provided or the captioned audiogram.

INTRODUCTION

Kevin Patton (00:01):
Writer Sarah Rosenshine once wrote, “If life hands you a painful irritant, cover it in an iridescent mucus-like substance until it becomes a pearl.”

Aileen Park (00:14):
Welcome to The A&P Professor. A few minutes to focus on teaching human anatomy and physiology with a veteran educator and teaching mentor, your host, Kevin Patton.

Kevin Patton (00:29):
This is episode 154, in which I try to convince you that mucus is our friend.

MUCUS & MUCOUS

Kevin Patton (00:45):
In this episode, we’re diving into a slippery subject, one that doesn’t always get the credit it deserves. It’s underappreciated, under-discussed, and honestly a little gross, but oh, oh, oh, is it important? That’s three “oh”s. That’s pretty high on my scale. Yep, we’re talking about mucus. In this episode, I’m going to give you 10 reasons why mucus is our friend and why I think it deserves more airtime in our A&P courses. I’ll even throw in a few slimy stories from my days as an aquarist and zookeeper. And as always, I’ve got some “brain breaks” to chunk of content and keep things flowing smoothly.

(01:40):
Before we get too far, I want to address something a little more foundational, a linguistic hurdle that often trips up our students. Yes, you guessed it. It’s the difference between mucus, M-U-C-U-S and mucous, M-U-C-O-U-S. You know those are two different words, right? Well, if you saw them spelled out, you’d know the difference, and that’s the problem. They sound alike when spoken, but they’re spelled differently and mean different things, and they’re both used frequently within the same discussions in A&P, often within the same sentence. The noun form, mucus, M-U-C-U-S is the gooey stuff that we’re talking about today. The adjective form, mucous, spelled M-U-C-O-U-S, is used to describe things related to that gooey stuff.

(02:46):
So a mucus membrane is a tissue that produces mucus. The membrane is mucous, the secretion is mucus. But when we say the membrane’s mucous, we’re using the word M-U-C-O-U-S. When we say the secretion is mucus, we’re using the noun form, M-U-C-U-S. Got it? One little letter, but oh, world of clarity. I know, I know, this isn’t a spelling or English class, but we are teaching professional language here, right? We’re teaching our students how to communicate clearly, precisely, and yes, professionally. And when they start using this language in front of future colleagues, professors, or patients, getting it right matters. So even if you’re new to teaching A&P or still finding your footing, I recommend addressing this early on. It shows students you remember what it’s like to be new, and it gives them the tools to avoid looking or sounding unprepared later on.

(04:05):
And fun fact, I’ve floated the idea for this episode to some colleagues, and every single one of them said something like, “Oh, are you going to talk about the two spellings of mucus? Because that’s a thing, you know?” So yes, I am. The answer is yes.

VIRTUAL HAPS CONFERENCE

Kevin Patton (04:27):
Hey, don’t forget to register for the HAPS Virtual Conference in October. Just go to theAPprofessor.org/HAPS, that’s H-A-P-S, and navigate to the conference page, then scroll down to the virtual conference link. This one promises to be even more fun than usual by adding some new elements. One new thing is a Presidents’ Series of keynote presentations by four past presidents of HAPS. I’ll be doing one of those. Mine is about audio-only media as another tool in our toolbox as we build and maintain our courses. All the keynotes and workshops will be in a flipped format. That’s new. They’ll be within Canvas, a learning management system that you may already be familiar with. You can watch recorded content on your own time, and then join scheduled, synchronous, moderated Zoom discussions with colleagues in HAPS. I’ll see you there, virtually, of course.

MUCUS: BODY-WIDE PROTECTOR

Kevin Patton (05:41):
Before getting to the first reason mucus is our friend. I want to clarify that. I’m assuming that you know the basics of mucus. That is, its general structure and function. What I’m doing in this episode is not that basic lesson. Instead, it’s organizing a list of ways to emphasize how important mucus is in our body, so that our students will walk away with a deeper appreciation of this amazing substance, even if it is kind of gross. So reason number one that mucus is our friend, is that it’s a mechanical barrier. Mucus is like your body’s biological Teflon. It coats vulnerable epithelial surfaces, your respiratory tract, GI tract, urinary tract, reproductive tract. Basically, anywhere your internal hollow organs meet the outside world. It physically traps dust microbes, allergens and more before they can invade deeper tissues and mess things up.

(06:57):
Think of it as the first layer of fortress walls, but they’re soft to squishy fortress walls. Do your students know that the average adult makes about one to one and a half liters of mucus every day? Most of it we swallow or reabsorb without ever noticing. Sometimes these surprising facts can really engage student interest, at least it gives them something to report When friends or family ask them what they learned in A&P today. “Yeah, I learned about mucus, and we make a liter to a liter and a half of that every day.” Fun facts, right?

(07:43):
You may already know that mucins are the glycosylated proteins that dominate mucus, but did you know that recent studies suggest that mucins can bind to viruses and help inhibit their ability to infect epithelial cells? So that’s reason number one, a mechanical barrier. Number two is mucus is an immunological first responder. Mucus doesn’t just sit there, it’s loaded with antibodies, lysozyme, lactoferrin, defensins—basically an arsenal of chemical weapons. Secretory immunoglobulin A, IgA, is especially important here. It’s our biochemical ninja squad, neutralizing threats before we even notice a problem. Newer insights also suggest that mucus can act as a staging ground for interactions between commensal microbes and immune cells. Now, here’s something your students might find interesting.

(08:54):
IgA is the most abundant antibody in the body, but mostly on mucosal surfaces, not in the bloodstream where I think students are thinking where all the antibodies are in the blood, and that’s not the case. There’s all these IgAs all over our mucosal surfaces. That gets us to reason number three, why mucus is our friend, and that is it’s a homeostasis helper, whether it’s maintaining hydration or buffering pH mucus is on the job. In the lungs. It keeps airways moist and gas exchange efficient. In the stomach, it shields the lining from acid.

(09:44):
Bicarbonate ions in GI mucous help neutralize acid and protect tissue from being digested. Current research on mucosal homeostasis is even looking at how mucus gets involved with epithelial repair mechanisms after injury. In the genital systems, mucus creates just the right microenvironments for fertility.

GROSS EPISODES

Kevin Patton (10:13):
Hey, since we’re focusing on one of the gross things in A&P, I want to mention that if you enjoy this mucus-focused episode… I guess it’s a mucous M-U-C-O-U-S episode, right? Because it’s describing the content of the episode, mucous episode, but it’s about mucus, the gooey stuff, so that would be… I don’t know.

(10:37):
Anyway, if you’re enjoying this episode, don’t forget to revisit a few classic gross episodes, one of which is the “poop episode,” and another of which is the “pee episode,” episodes 19 and 27. We dig into feces and urine, well, metaphorically, of course, and what these gross substances tell us about physiology. It’s everything your students didn’t think they wanted to learn, but totally need to.

MUCUS IN MOTION

Kevin Patton (11:15):
Well, now we’re up to reason number four, why mucus is our friend, and this one is lubrication. Mucus is your body’s built-in lubricant. In the mouth, mucus lubrication helps us talk and swallow in the gut, that lubrication eases food along. In the genital system, it facilitates sexual activity and sperm transport. In a way, it’s our body’s WD40, allowing all the different things to sort of slide past one another. Salivary mucins are the proteins that give saliva its slippery texture. Different mucins show up in different tissues, tailor-made for the task. In recent years, synthetic mucin-like materials have even been developed for use in bioengineering and medicine.

(12:22):
Reason number five that mucus is our friend, is that it makes up a trap-and-transport system. This is where mucus teams up with cilia in the respiratory system, for example. Together, they create the mucociliary escalator, often shortened to just ciliary escalator, and that traps particles, microbes, and debris, then moves them out of the lungs. When this system breaks down, like in cystic fibrosis or bronchitis, bad things happen. In this transport system cilia beat in coordinated waves at about 12 to 15 times per second. Current research is exploring how hydration levels and mucin gene expression affect this transport system’s efficiency.

(13:21):
Reason number five that mucus is our friend, is that it acts as an environmental sentinel. Mucus is dynamic. It changes its consistency in response to illness and environmental stress. Thick green snot, oh, that’s not a failure, that’s defense and action. The color, texture, and even smell of mucus give clues as to what’s going on internally. That green color, it’s from myeloperoxidase, an enzyme from our trusty neutrophils. Mucus also acts as a biosensor in a way, alerting clinicians to shifts in health status long before invasive tests might. Here’s an example of how environmental exposures can change the color of mucus that forms our snot. In the olden days when I was a zookeeper, I once had to pitch dry alfalfa into a very high giraffe manger, bolted to the wall in the giraffe exhibit.

(14:32):
Being a short guy and not having any prior practice, pitching alfalfa into such a high target, this was a lot more challenging than it sounds, and not all my shots on the basket made it in the first time. When I was done, I felt a little stuffy and I blew my nose, and out came a thick greenish-black mucus. But it wasn’t infection causing the discoloration, it was alfalfa dust. That nasal mucus caught and removed airborne particles before they hit my lungs, or at least it removed some of it, thankfully.

(15:22):
I’m wondering now if there’s such a thing as “giraffe lung” that former giraffe keepers might suffer from. I have noticed though, that the zookeepers working in the very same facilities that I did are now required to wear special masks that keep the alfalfa dust out. That’s a good move, I think.

KERRY HULL HONORED

Kevin Patton (15:46):
Hey, I wanted to take a moment to congratulate my friend Kerry Hull, who’s presented with the 2025 HAPS President’s Medal at the recent conference of the Human Anatomy and Physiology Society in Pittsburgh. Kerry has long been one of my heroes for sharing her many insights, skills and hard work to help the international community of A&P educators. Besides her awesome service, she’s just an awesome, empathetic, brilliant, fun colleague and friend, loved and respected by all. Congratulations, Kerry.

MUCUS & THE HUMAN STORY

Kevin Patton (16:29):
Well, getting back into the goo, let’s think about the role of mucus as a microbiome habitat. That’s reason number seven why mucus is our friend. In the gut, mucus doesn’t just block pathogens. It creates a habitat for friendly microbes. Some bacteria even feed on it. It’s part of the border between the internal and external environment, and it’s managed to help maintain the balance of the microbiome. In the colon, the outer mucus layer hosts bacteria. The inner layer is usually sterile, and mucins themselves are being studied as communication tools, carrying signals between microbes and host cells. One of the benefits of dietary fiber is that it ferments and produces short-chain fatty acids that help support mucus production by the gut epithelial cells. If our diet is low in fiber, then of course that disrupts the protective functions of the GI mucus coat, which can lead to all kinds of health problems.

(17:47):
Reason number eight that mucus is our friend, is that it facilitates fertility. Something I mentioned very briefly early on. Cervical mucus, for example, is a major player in fertility. Around ovulation, it becomes thin and slippery, perfect for sperm transport. It forms fibrous channels that guide sperm toward the egg. At other times, it thickens and becomes a barrier. By the way, around the time of ovulation, cervical mucus crystallizes, or “ferns,” under a microscope. Yeah, it looks kind of like frost on a window. Current investigation in fertility science is looking at cervical mucus as a non-invasive fertility diagnostic. Reason number nine that mucus is our friend, is that it’s a digestive ally. Mucus in the GI tract prevents autodigestion that is digesting ourselves, digesting our own tissues, and it protects the epithelium. It also helps chyme and move along without damaging tissues. Think of it as the gut’s shock absorber. MUC2 is the major mucin in intestinal mucus, and it forms a physical slippery barrier. Some ulcerative colitis research is now focused on disruptions in this specific mucin and the mucus barrier that it helps build.

(19:31):
Reason number 10, that mucus is our friend, is that it’s a powerful indicator of health. Sometimes mucus tells stories, as I’ve already mentioned, changes in color, thickness, or content can indicate infection, inflammation, or environmental exposure. I gave the example of exposure to alfalfa dust and giraffe keepers. That makes mucus a powerful diagnostic clue if we pay attention to it. Another example is frothy, pink sputum in pulmonary edema is a sign. Yellow, green phlegm in infections can be an indicator of things going on. Bloody mucus, that could be a red flag. And today, digital tools are even being developed to analyze these properties in point-of-care diagnostics. So maybe before long, healthcare workers are going to be carrying around mucus scanners to figure out what’s going on in our body. You never know.

RUNNING CONCEPT LISTS

Kevin Patton (20:42):
Hey, here’s a quick reminder. If you missed episode 41 on “running concept lists,” go back and check it out. Mucus is a great example of a concept that shows up everywhere in the body, and therefore everywhere in the A&P course. So call it out and emphasize it across the course and watch your student’s understanding deepen.

MUCUS IS VITAL

Kevin Patton (21:11):
Well, now we’re ready for reason number 11 that mucus is our friend, and that is that mucus is vital. Disrupted mucus can kill. What? Wait, wait a minute. Number 11? Isn’t this episode all about the 10 reasons mucus is our friend? I mean, that’s in the title. Well, yes, but besides my habit of nearly always having one more thing to say on just about any topic, this one isn’t really about human mucus. Number 11 isn’t about mucus being our friend as much as it’s about mucus being the friend of fish.

(22:02):
Another animal-related job that I had in the olden days was as an aquarist. That is a professional who designed, built and maintained aquarium habitats and the animal and microbial communities living inside them. And one of the key concepts of keeping fish healthy is to help them maintain their slime coat, which covers the entire exterior of their body. You’ve probably touched a living fish, right? You’ve experienced that slimy mucus coat then. And by touching it, you’ve also disrupted it. As we’ll see in a moment, that could be bad. Fish mucus has the same kinds of functions as human mucus, but these roles are expanded in fish, and as we found out in our aquarium profession, a key to their health and survival in the stressful artificial world of an aquarium tank.

(23:06):
One key function of the slime coat of fish is protection against infectious agents and physically harmful particles or chemicals. If the fish slime fails, even in just a small area of a fish’s body, it could soon result in infection or injury, pain, and the accompanying stress, which may then lead to suffering and death. Another function of the mucus in fish slime is lubrication. It’s harder to glide through water without that fish slime. Since fish glide all day and night, a breakdown in lubricant is also very dangerous. You know what we did to prevent slime issues in fish? We used something like an artificial fish slime every time we did any kind of management or maintenance activity in the tank. These tasks are stressful for fish, especially netting or grabbing a fish and transferring it to another tank. But even things like leaving the fish in the tank and just partially changing the water or adding, or removing other fish, or moving objects around in the tank can be stressful and damaging to the fish’s slime coat.

(24:33):
You can buy versions of this product in any aquarium shop. They’ll have a lot of it in stock because it works really well. By the way, none of these are exactly a complete artificial slime solution, but they have components that supplement or enhance the mucus coat during stressful aquarium conditions. They also make sure the water condition is okay, which helps too. One popular version of this product is called Stress Coat. That’s the brand name, Stress Coat, which makes sense, right? Another product which I named when I was consulting with a fish health company was called Ultra Shield. I thought that sounded a bit more positive than Stress Coat.

(25:22):
The point is that fish will die if their slime coat is disrupted. That’s true in nature, and it’s true in an aquarium, and if the human mucus coat found lining many hollow organs where the external environment meets the internal environment, if that gets disrupted, yep, that can kill us too, unless we prevent it or treat it effectively, perhaps by using a product that coats our oronasal lining, our esophagus, our stomach, or our genital membranes. Maybe reason number 11 is about human mucus, after all.

STAYING CONNECTED

Kevin Patton (26:05):
Mucus in its various forms might be the punchline of a lot of jokes, but in the world of A&P, it really does deserve top billing, or at least billing somewhere higher than it usually is. It’s a barrier. It’s a lubricant, a communication tool, a microbiome manager, a fertility assistant, a canary in the coal mine. There’s way more to learn about mucus and many more fun facts and surprising current research. So I provided links to some of the mucus resources in the show notes that you can probably access where you’re listening right now, and also on the web at theAPprofessor.org/154. That’s theAPprofessor.org slash 1-5-4. I’m encouraging us to elevate our discussion of mucus, make mucus a recurring character in the story of the human body that you tell in your course. Encourage students to follow the mucus wherever it leads, because if they do, they’ll see how the body is built and how it works more clearly, and they might even spell it right in the correct context.

(27:23):
So if you have a mucus story or anything else you want to share with our community of anatomy and physiology professors, just call us on the podcast hotline at 1-833-LION-DEN. That’s 1-833-546-6336. Thanks for sticking with me through this whole mucus episode. Until next time, stay connected, stay curious, and of course, stay moist. I’ll see you down the road.

Aileen Park (27:59):
The A&P Professor is hosted by Dr. Kevin Patton, an award-winning professor and textbook author in human anatomy and physiology.

Kevin Patton (28:11):
So many mucus puns have slipped and dripped into this episode, that some listeners may find it disturbing.