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We’re All Just Big Slime Buckets!

And that’s a good thing. Why you should appreciate your sliminess.

As you may remember, in a previous article I told you about my personal history and battles with mucosal slime.

And I said that due to some new discoveries, we’d get explanations for some of those conditions.

Let’s start with a typical scenario.

Say your kid (or your partner or best friend or someone at work) has been running around with a stuffed up drippy nose all week and now your own nose is getting stuffed up and drippy. And you think, shoot, I’m coming down with a cold! I hate being sick.

But maybe you’re not. Getting sick, I mean.

Maybe all that slime is actually doing something good for you.

What!! How could it be good for me? I get it, I know I’m getting sick.

Well…what do you really know about stuffy noses and mucus?

Do you know all the other places in our bodies besides our noses that produce and use slime? And how it’s essential to our staying healthy?

No? Well, I’m not surprised, neither did I.

So let’s learn a bit more about our slime, or its biological name, mucus, and how it’s both a bother and a benefit for us.

Where is the mucus in our bodies?

Mucus is found all over our bodies. It is found in our sinuses, nose, mouth, throat, lungs, stomach, urogenital systems, and in the eyes and ears. Most of the mucus in the body is produced in the gastrointestinal tract.

Mucus in the respiratory tract. There is a fluid that coats almost all of our respiratory tract called epithelial lining fluid or airway surface liquid.

This fluid is made up of 2 layers, one a gel made up of various molecules and the other is a mucus “blanket” which lies on top of the first layer. This mucus layer is about 95% water and its purpose is to trap and prevent the foreign particles that enter during normal breathing through the nose or mouth from getting into our lungs.

Phlegm, another form of mucus, is a juicy secretion formed during disease or inflammation. When it is coughed up it is called sputum and is produced only in the mammalian respiratory system and is excluded from the nose.

Interesting fact: Your body naturally produces about a quart of phlegm every day to capture and clear substances and microorganisms in the air from your nose and throat.

Many upper respiratory ailments such as influenza or the common cold can cause increased mucus production which is often “treated” with over-the-counter decongestants. However, you have to be careful with their use as you can get a rebound effect from overuse of these medications. If you read Part 1, you know that this is what happened to me. They can actually cause the mucus to thicken which then causes drainage problems that actually promote infection.

If you are a person with asthma, cystic fibrosis or chronic obstructive pulmonary disease, you produce too much mucus and it has different physical properties than healthy mucus. As a result of the change in the structure of the gel, your airways can’t clear the mucus. This leads to poor gas exchange, inflammation and permits bacterial growth which can lead to disease.

So there are different kinds of mucus and we need the good, health-promoting kind.

What is Mucus?

Mucus is the substance produced by a mucus membrane, also called a mucosa. It is a thick protective fluid and is aqueous and slippery, hence the slimy feel.

The reason it’s so thick and slimy is that it is a polymer. A polymer is a large molecule made up of many connected subunit molecules. One way to visualize a polymer is to think of it as a long freight train. Each train car is a subunit molecule, all the cars are connected so the whole train from the engine to the caboose is the polymer.

Mucus can also contain many different substances including inorganic salts, enzymes that fight microbes, immunoglobulins, glycoproteins and other biomolecules.

Technical information aside, for our purposes just remember that mucus is usually secreted for lubrication or as a protective barrier for its antimicrobial and other properties.

Interesting aside: Amphibians, fish, hagfish, snails, slugs, and some other invertebrates also produce mucus as protection against pathogens and to help in movement. Mucus is also produced in fish and lines their gills. Plants produce a similar substance called mucilage that is also produced by some microorganisms.

Mucins and Glycans

The long thread-like polymers that form mucus are called mucins. Mucus also contains glycans, also called polysaccharides, which are complex carbohydrates. Mucins and glycans often get together to form a complex which helps to protect against bacterial infections.

We normally make the good kind of mucus. How does it help us fight infections?

The bioengineering laboratory of Dr. Katharina Ribbeck at MIT has researched mucus to try to understand what its role is and how it works. Her group has come up with some interesting findings.

Studies conducted in the Ribbeck lab showed that mucin-glycan complexes have a profound effect on both the friendly microbes normally associated with our bodies (our microbiome) and the pathogen microbes that can cause us harm and disease.

It turns out that particular mucin-glycan complexes actually prevent harmful bacteria from entering and infecting our bodies and they do it in several ways.

These ways include affecting their ability to move or “swim”, their ability to settle and their ability to communicate with each other.

In some harmful infections, bacteria form what is called a biofilm. This is a different kind of slime, a “mat” that includes millions of bacteria and once established, sets up a barrier that makes it difficult to get to the harmful microbes. Our immune cells which would normally seek out and destroy them have a hard time gaining access to them.

One example of a biofilm that you are probably familiar with is our dental plaque. I’m particularly susceptible to those guys and have to get my teeth scraped clean every 3–4 months to prevent those bacteria from eating away at my teeth.

In an important series of experiments, the Ribbeck lab grew Pseudomonas aeruginosa, a bacteria which causes infections in people with cystic fibrosis and people with compromised immune systems. When P. aeruginosa was grown in the absence of mucus, the bacteria grew well and formed a biofilm.

But when they were grown in the presence of mucus the P. aeruginosa microbes failed to form a biofilm and were not as numerous.

Here’s a 4 minute Ted Talk video they made that describes how the mucus does that.

So if the bacteria can’t form a biofilm, they are more easily eliminated by our immune system.

Which brings us back to that stuffy nose we were getting. Your body is setting up its defence systems to help keep you from getting sick!

Maybe instead of thinking that we’re getting sick, we can perceive it as our body mounting an attack against the enemy so that we stay as healthy as possible.

It may be better to suffer a runny nose for a few days and get less sick. And if you do ultimately succumb to the disease, know that your body tried to keep that from happening by making the good slime.

So don’t always try to immediately get rid of that mucus-filled nose unless you have a major presentation or big date that you have to get ready for.

In my last article about mucus, we’ll look at the genetics of mucus and a few diseases that arise from “bad” mucus.

Unt…..ii….llllll…….AAAAACHOOOO!! Later,


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Rich writes about fascinating creatures and biological issues that affect our everyday lives. Subscribe and get your free ebook at

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