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Ep. 9: Skin Basics

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Ep. 9: Skin Basics

Nov 03, 2021

What does our skin do for us? How about our hair and nails? And how do we help skin to function at its best? In this episode of Skincast, hosts Luke Johnson, MD and Michelle Tarbox, MD cover the basics of how our skin, hair, and nails work in order to help us better understand how to fight acne, why to use sun protection, and more.


Dr. Tarbox: Hello, and welcome to "Skincast," the podcast that teaches you how to take the very best care of the skin you're in. I'm Michelle Tarbox. I'm a board-certified dermatologist and dermatopathologist at Texas Tech University Health Sciences Center in beautiful sunny Lubbock, Texas. And joining me is . . .

Dr. Johnson: Hey, this is Luke Johnson. I am a pediatric dermatologist and general dermatologist with the University of Utah.

Dr. Tarbox: Today, what we're going to talk about are skin basics. Basically, what is the function our skin is supposed to do and how do we help our skin do those functions to its best ability? So what's one of the most important functions of skin, Dr. Luke?

Dr. Johnson: Well, the skin does a lot of stuff. It's really cool. So, obviously, Michelle and I think it's cool because we're skin doctors. And this is going to be kind of a nerdy episode, because we all like to geek out about the skin in dermatology.

One of the many things it does is regulate your temperature. So the skin has some stuff under it, fat and so on, which is also lumped in with the skin sometimes when we talk about the skin and dermatology. And that all helps you stay warm when it's cold outside or stay cool when it's hot outside, sometimes by things like sweat.

Dr. Tarbox: Absolutely. And one of the other really important functions that our skin performs is helping act as a barrier to the outside world. It's where our body and all of the things that we have contained within us come into an interface with the external environment. So it's one of the things that needs the best defense and also helps us to maintain our first line of defense against things like bacteria and viruses.

Dr. Johnson: The human body is amazing, and sometimes we don't really appreciate what it's doing until it's doing it wrong. So patients, for example, who have problems when they can't sweat, they get overheated. And patients who have a problem with the skin barrier function can get diseases like eczema.

The skin is also perhaps the biggest immune organ in the body. There's a whole bunch of immune cells in the skin, as you might guess, since it's interfacing between our bodies and the outside world.

Dr. Tarbox: Absolutely. One of the places that we actually have the sort of interplay between our primitive fast innate immune system, which is the very quick reaction our immune system can have against a general category of things like bacteria or virus, versus a very specific immune response, something more like what you get triggered when you have a vaccine.

Dr. Johnson: People who have problems with their immune system then get more infections in their skin, and perhaps elsewhere, since the skin is the first line of defense in a way.

And of course, human beings are social creatures, and so one of the main things our skin does is indicate to other people, well, various things. Other people can see our skin, and so obviously, there are big cosmetics industries and so on like that.

Dr. Tarbox: Many parts of our skin have specialized functions and things that we can do to sort of help those to act better and work better for us. Some of the very specialized organs of the skin include our hair, our oil glands, our sweat glands, our nails, and mucous membranes. So let's talk about hair first, Luke.

Dr. Johnson: Okay. I have a great set of hair. How about yourself?

Dr. Tarbox: You really do. You have lovely hair. I was blessed with very curly hair, which I really enjoy. Something a lot of people don't realize is that the hair on our body, but also on our skin, also helps us in a sensory way. So there's actually a little grouping of nerve fibers called the hair plexus or the root hair plexus that actually is a mechanoreceptor for touch sensation. So that's part, of course, of our normal skin like our arms or our legs.

But also, some people believe that you can actually have some sensations through the hair on your head. In some native communities, people feel very strongly about keeping the hair long as sort of a mechanoreceptor to help perceive the external environment.

Dr. Johnson: Dermatologists take care of the skin, but we also take care of the skin friends, like hair, and perhaps if you have problems with oil glands or sweat glands or nails or mucous membranes, dermatologists can help with that, too.

Oil glands are in a lot of places in our skin, but we often think of them primarily on the face because they can cause problems like acne. The special kind of oil that these glands have is called sebum.

Dr. Tarbox: That sebum helps to protect and nourish the skin and keep that barrier to the world waterproof. When it's not functioning properly, people get really dry skin that looks like a dry riverbed and cracks. That causes itching, it lets air in, and possibly lets in other contaminants as well. So that oil is actually very important.

Dr. Johnson: We have a couple of different kinds of sweat glands in our skin. There are sweat glands called eccrine glands and sweat glands called apocrine glands. Most of the sweat glands on your body are eccrine glands and they produce the sweat that you're probably most familiar with. But in places like your armpits and other big skinfold areas, you have apocrine sweat glands, which are a little bit different, sometimes a little bit smellier.

Dr. Tarbox: The sweat glands respond primarily to temperature stimuli, so they can actually help us to cool ourselves off if we overheat. But they also respond to emotional stimuli. So if people are getting really anxious or if they're very upset, they might sweat a little bit more.

Apocrine sweat has some fascinating functions. Some people actually believe that it's very important for pheromone signaling, which was, of course, more important before we could use conversation and lovely dialogue to convey our feelings to each other. But even in these modern times, those sorts of pheromone hormones do seem to play a role in people's attraction to each other.

Dr. Johnson: And again, we notice when things go wrong. So there are people who have a condition called hyperhidrosis where they just sweat too much. And then that's where dermatologists can help and use some medicines to make them not sweat as much. But imagine if you were just sweaty all the time what a pain that would be.

Dr. Tarbox: There are also some people who have a condition called bromhidrosis, where the sweat that they make actually smells a little bit more intensely than other people's. And there are also good treatments for those as well.

One of the fun things we share with the animal kingdom and those other creatures that live in the mammalian group like we do are our nails. So our nails are basically our version of claws. What are our nails for, Luke?

Dr. Johnson: Well, they're probably not all that relevant in the modern world, but they can be involved in picking up small objects, like when our ancestors had to pick up a nickel off of a smooth wooden table. Nails were especially helpful for that. These days, of course, they're often used to signal to other humans. So people put on nail polish and fake nails and things like that.

Dr. Tarbox: They also protect the ends of our fingers and toes, which are subject to more rough and tumble activities, and they're also helpful for some sensation. So they can actually help us to sort of feel certain types of things. And of course, we also like to express ourselves sometimes through painting them different colors or keeping them longer or shorter than other people.

Dr. Johnson: Mucous membranes include things like your mouth, and your eyes, and your nose, and your genitals. They are pink and moist and sort of related to the skin as well. They're a little bit like skin without the top layer.

Dr. Tarbox: Our mucus membranes can experience similar diseases to the rest of our skin. There are some problems when we have skin that's too dehydrated in those mucous membranes, or conversely when the skin is too wet all of the time.

We also have to worry about barrier dysfunction. For some people, they have a little bit of abnormality in the way their skin cells mature in those mucous membranes. And that can cause pain or it can potentially cause itching in those areas that can be treated.

Dr. Johnson: There are specific diseases that can affect the mucous membranes. So if you are worried that you have one of them, then a dermatologist might at least be a good place to start. Sometimes we rely on our colleagues in ENT, or dentistry, or gynecology to help us out, but we know a lot about mucus membranes, too.

Dr. Tarbox: And we're fortunate that most of our mucous-membrane-lined areas are actually self-cleaning and really take pretty darn good care of themselves. Of course, normal oral hygiene takes good care of that oral mucosa, and being gentle to the other areas is always a good strategy. You don't want to do anything too harsh or too irritating in those mucous membrane areas.

Dr. Johnson: I'd like to talk a little bit more about how to keep our skin, etc., healthy. So one thing you can do is moisturize your skin. I should say that if you don't really have any trouble and aren't bothered by something in your skin, then maybe you don't need to do some of this stuff. But a lot of people end up getting dry skin, especially if they're doing things like washing their hands a lot. It's still the coronavirus era, very sadly, so people are still washing their hands a lot. So applying a moisturizer can really help.

Dr. Tarbox: We also need to think about our exposure to the sun. One of the cool things about our skin is that it actually produces its own special sunscreen. There's a chemical called urocanic acid that's actually found in the stratum corneum, that outside top layer of the skin. And that actually comes from breakdown of other skin proteins, but it is actually able to prevent some sun damage. However, usually, it's not quite enough for much of our sun exposure, so we have to be thoughtful about our time in the sun.

Dr. Johnson: We have a whole episode on sun protection, so if you want more details, check it out. But basic story is use sunscreen and use sun protective clothing like long sleeves and hats as well.

I should say that the sun isn't all bad. One of the functions of the skin is to use sunlight to produce vitamin D, but you really don't need to be out in the sun for very long in order to get how much vitamin D you need.

So there are some medical studies that say if you spend eight minutes, three times a week out in the sun wearing shorts and a T-shirt, that's enough. So don't not use sunscreen because you're worried that it's going to inhibit your vitamin D production. You'll be fine.

Dr. Tarbox: And then of course, one of the other things that we can do for our skin is keep it clean. Now, for most of our skin surface areas, like the skin on our arms or legs, unless we've gotten into something actually dirty, we just need water running over the surface of that skin to cleanse it.

However, there are certain parts of our body that do need to have some sort of cleanser used. And those include our areas that have more oil secretions or more apocrine secretions. So that's going to be your face, the great folds of the skin, the hands, and the feet.

Dr. Johnson: Yeah. So if you, again, don't have problems with your skin, you don't really need to worry about it, but if you want to keep your skin not too dry, then what I normally recommend is no soap except in the "problem areas," which are the armpits and the groin. And then, of course, you can wash your face too.

And use gentle products. There are a lot of skincare products out there on the market, and some of them are just fairly harsh on the skin, things like astringents and scrubs and so on. They're pretty tough on the skin, so you don't really need stuff like that. Keep it gentle.

Dr. Tarbox: A gentle, nice, pH-balanced soap without too much heavy fragrance and with gentle preservatives is probably the way to go for most people.

Dr. Johnson: We aren't sponsored by anybody, but we do like to provide specific product recommendations just because I think it's helpful. So kind of the party line among most dermatologists for soap is white Dove bar soap. It's a good inexpensive option that's nice and gentle.

Dr. Tarbox: We also like a couple easy-to-find, over-the-counter products for cleansers, especially for people with sensitive skin, including the CeraVe cleansers or the Cetaphil cleansers. So how else can we keep our skin looking nice, Luke?

Dr. Johnson: So keeping it looking good is important to a lot of people, again, as evidenced by the multi-billion-dollar cosmetics industry. So I would lean on you to provide some cosmetic recommendations, Michelle, because I'm afraid I don't actually use any cosmetic products myself.

Dr. Tarbox: Well, once you have the basic groundwork of having a nice gentle cleanser that works well with your skin, as well as also having a nice sunscreen that you tolerate well and use regularly, other things that you can do to help improve the appearance of your skin include using an over-the-counter or prescription retinoid. Retinoids are vitamin-A-type products that help our skin cells turn themselves over. They help renew that skin, and they also help fight uneven pigmentation and fine lines.

Dr. Johnson: Retinoids are awesome. I do use a retinoid. So if you consider that cosmetics, then I misspoke earlier. But they're in a lot of over-the-counter products that have names like anti-aging or anti-wrinkle because, indeed, they do those things.

And the specific ingredients will be things like retinol, or retinal, or retinoic acid, or adapalene. Dermatologists can provide you with prescription-strength versions of these things as well. They're also good to help prevent acne.

Dr. Tarbox: You also want to think about good moisturizing ingredients. One of the best ingredients for skin moisturization is called a ceramide. This is sort of the lipid or fat that our skin makes to hydrate itself. And it really helps to have that kind of moisturization for our skin to look its best.

Dr. Johnson: Hyaluronic acid also a very good moisturizer because it holds a lot of water. In general, as far as moisturizers go, the thicker and greasier they are, the more effective they are at moisturizing the skin. But, of course, most people don't want to put something super thick and greasy on their face. So you've got to find the right balance.

Dr. Tarbox: Absolutely. You have to treat your skin, not somebody else's skin, not an influencer's or somebody that you aspire to be, but your skin, the way that it actually behaves. So if you have oilier skin, you may want to look for a moisturizer that's a little bit lighter and made for patients with oily skin. If your skin is very dry, you might want one that's a little bit more rich and thick that's made for more mature skin or more dry skin.

Dr. Johnson: Sometimes I have patients ask me about specific cosmetics like makeup and so on. And I normally tell them, "I'm afraid I don't actually know all that much." But I normally recommend those with the fewest ingredients because that's least likely to become irritating. So things that are mostly mineral-based. I think there's a brand called bareMinerals that I tend to recommend. Do you have any specific recommendations about makeups?

Dr. Tarbox: I do like bareMinerals. I like to make sure patients are actually getting the branded bareMinerals, or are making sure that there are not a lot of fillers in a similar product. A lot of powder-based makeups have talc as a filler, and that's actually not very good for your skin. So trying to avoid that is a good idea.

Other things you want to avoid, again, are heavy fragrance, things that have harsh preservatives, and things that are made that are just not really put together in a way that's good or safe for your skin. You can always find a label on products that are made for skin and thoughtfully that has some kind of indication of whether or not it helps or fights the formation of acne. So you want to find a product that says non-comedogenic, which is sort of the first form of acne, or non-acnegenic to make sure it's not going to make you break out.

Dr. Johnson: Keeping your skin looking good is also another reason to protect yourself from the sun, because the more sun exposure you've had over the course of your life, the wrinklier and saggier your skin.

Also, if you've been out in the sun a lot and you're in your 60s or older, you might start getting these bruise-looking things all over your arms and the backs of your hands. That's, again, mostly from sun exposure. So if you want to keep yourself looking youthful, make sure you use that sunscreen.

Dr. Tarbox: One of the other things that can tell on our age are our hair and nails. Those are really great reflectors of what's going on inside our bodies. So sometimes patients will suffer from some kind of an illness or significant stress or start a medication that doesn't agree with them and their hair will shed significantly. So what would be some reasons to see a doctor for that, Luke?

Dr. Johnson: Well, if any part of your skin, hair, nails, or mucus membranes doesn't seem like it's going right, then come see a dermatologist. We can probably help.

As far as hair specifically and hair loss, the best thing to do is to see one of us fairly quickly, because most of our treatments are pretty good at preventing further loss, but not so good at re-growing hair, though they can do that to some degree, so all hope is not lost.

We have an episode on "Skincast," I believe Episode 3, that's all about hair loss. So if you have more interest in that, check that one out.

Dr. Tarbox: So I think that we've talked about what are good ideas about taking good care of your skin. I think we talked about when to see a dermatologist. Any other pointers you want to give our listeners, Luke?

Dr. Johnson: Yeah, you should listen to the rest of our archive, which you can find through the University of Utah. Thanks to them for supporting the podcast, and thanks to Texas Tech for lending us Michelle.

If you enjoyed this very nerdy discussion about skin, then you might also enjoy a very nerdy podcast that Michelle and I do called "Dermasphere," which is really intended for dermatologists, but it's got discussions about some of the latest research in clinical dermatology. So you might find it cool whether you're a dermatologist or not. We'll see you guys next time.