Hello, and welcome to this Skin Deep podcast, where we'll be looking at skin-related issues and treatments in, what I hope is, an interesting and informative way. I'm Dr Roger Henderson, and I'm a GP with a long-standing interest in this area of health. And I'm Dr George Moncrieff. I was also a GP, though I retired from my practice a few years ago. I'm also the past Chair of the Dermatology Council for England.
Today, Roger and I will be talking about some skin basics, including why our skin is so vital for our health. Now, I think many people listening might actually be quite surprised to learn that their skin is their biggest body organ. And indeed, they might not actually think of it as being vital to their health. It really is so vital to their health. But, asking what may sound to be a simple question to kick off, I suppose, just why is our skin so important to us?
Well, as you say, it's certainly a very big organ. It measures, on average, about two square metres. And surprisingly, actually, it's been taken over by fat tissue in our modern society. Adipose tissue is now beginning to become a larger organ. But apart from that, the skin is, as you say, the biggest organ in our body. And it is the interface between our sterile, well-controlled, internal environment and this hostile world we live in.
A world full of microorganisms and it's the skin that protects us from these bugs, these bacteria, viruses, fungi and other nasty creatures getting into our body. Um, but it also stops us from becoming dehydrated. When a baby is inside the womb, it's in a lovely, warm, humid environment. There's, no need for a skin barrier. But within a few hours of being born, a baby has to, amongst many other adaptions, has to develop a skin barrier to prevent water evaporating.
And if the baby doesn't achieve that, they will die from dehydration. So it's critical for preventing water loss. It's also involved in controlling our body temperature. So if we're in a hot environment, it enables us to lose heat through sweating, and, water evaporating off the skin. But, equally, in a cold environment, it helps us to conserve heat by restricting the amount of blood flow that goes to the skin. So, critical roles in thermoregulation.
It's also the organ that has our sensory organs. So it's our skin that lets us feel what the temperature is and pain and touch and all other sensations, which are so vital to us. And then in addition, the skin is involved in things like vitamin D production, um, and so on. But also when the skin is diseased, when there's a rash on the skin, it's visible. And that can have a devastating impact on patients, um, psychologically.
Hardly surprisingly, it affects their self-esteem and it affects how they interact with other people, affects job opportunities. It affects relationships. It has a catastrophic effect on, on wellbeing in so many areas. Well, that's interesting, George. You and I, of our long experience of seeing people with skin disease, both know that if they have significant skin disease, psoriasis would be a good example or, you know, significant eczema, what's the first thing they do? They cover it up.
Yeah. [They] don't want it to be seen. And the impact of that, and we'll talk about this in future podcasts, but the impact of that is huge. So yes, the psychological impact. I recall vividly a young girl, about 14, who came to see me with terrible acne on her face and sitting there with her hair all down in front of her face. I wasn't sure which way she was facing. I thought she might be facing [backwards] because all I could see was this hair completely covering down the front of her body.
As if I was looking at the back of her head. She really was so distressed by the appearance of her face and this is a beautiful, young woman who happened to have quite severe facial acne. It can be really devastating. The most extreme example, I suppose, George, and it's almost a terrible thing to think about, is when people have severe burns. The reason why people with severe burns die is directly because of their, skin loss.
Modern medicine is remarkable, but it still cannot cope with someone who has 80, 90 plus percent burns because of the impact of losing their skin. I suppose that's a dramatic example of just how important skin is to us and what happens if we lose it. But it's such a complicated organ. The two major problems that they face in those first few days are, of course, infections getting in and, affecting the skin and water loss. Keeping up with that water loss through that damaged skin.
Those are the two critical things that, in the first few days after a severe burn, would kill a patient. Absolutely and we've tragically all seen that. I mean, skin structure as such, you know, you might look at your skin and think, "Well, that's just a bit of skin". The skin structure is actually, not only remarkable, complex, but also absolutely crucial.
What do you think we should be knowing really about our skin structure to help us understand just how it works and what a magnificent organ it is? It is truly magnificent. It really is and the more I look into it, the more amazed I am at how magnificent it is. Under the skin we have fat tissue. What's called the subcutaneous, meaning under the skin fat, which buffers, um, the skin and by buffer I mean, if you knock it, it doesn't hurt the bones underneath.
It's soft and it, overlies things and, sort of, moulds over, contours quite nicely. But the skin itself is made up of two main layers. The deeper layer, called the dermis, which is where your hair follicles are and most of your sensory organs are. Then the top layer, which is called the epidermis. Now the epidermis is actually very thin. In some parts of the body, for example on the eyelid, it's half as thick as a piece of paper. It's incredibly sophisticated.
The cells mature as they move to the surface. These cells are growing up from the junction between the dermis and the epidermis. They're growing up to the surface and as they grow, they change their structure and change their shape. The very top layer of the skin we call the stratum corneum and that top layer is the skin barrier. The cells here are amazingly adapted to live in this dry, hostile world that we live in. They have a, they're very long cells. They've been stretched out.
So there's enormous overlap, one on top of another. And they're held together by very, very strong bonds that are created in that top layer of the skin to hold them together tightly. Those bonds are broken in a very carefully, orchestrated way so the top layer just falls off at the right time. In between the cells is a fatty layer called the lipid lamellar bi-envelope.
It's fat that, sort of, fatty material made up of things like ceramides and triglycerides, cholesterol and things like that, which seals the gaps between the cells and confers some flexibility to the skin and to the surface. But the other thing, in fact, is that in the process of making these changes, which is orchestrated through a very large protein called profilaggrin, which breaks down into filaggrin.
That is broken down also into a huge number of very small molecules, and all these molecules draw moisture to them. They're what's called 'hygroscopic'. They even draw moisture from deeper in the skin into that cell, pumping it full of water so it's pumped up tight against its neighbours. The other remarkable thing about all these small molecules is they're all acids. Most of them are fairly weak acids, but they're acidic. And that drops what's called the pH.
It makes the skin more acidic on the surface. Deeper down in the skin, only a millimetre or less, the pH is neutral. But when you get onto the surface, you have this acidity, which is so important. It's called the acid mantle. And that acid mantle controls the activity of the chemicals, the enzymes that break down those bonds in that beautifully orchestrated way I was talking about.
But it also favours the adhesion of healthy bacteria, which is what we need on our skin, and also kills pathogenic bacteria. So that acid mantle is really important. I'll be talking more about the acid mantle in this series. So that's just a very quick glimpse into how remarkably clever it is. Deeper in the skin we make almost 2,000 different, natural, antimicrobial peptides. Our body's natural antibiotics.
So the skin has this critical immune role at killing bacteria that penetrate it and other ways in which it deals with bad bacteria and viruses and things that get in. It's remarkably sophisticated and, um, remarkably well-adapted for this dry, hostile world we live in. I think a lot of people would be really surprised at just how complicated it is. I think a lot of the time we think skin is skin and actually don't give a second thought.
You know, it is as complicated as the heart or the liver or the kidneys or any organ you want to think of. And I haven't even started talking about the role of hairs... No. [Laughter] ... or sweat glands, or grease glands, or sensory organs, or so many other things that are going on there. It is utterly fascinating. Absolutely. Huge thanks to AproDerm® for all their help in putting these Skin Deep podcasts together. We couldn't have done it without them. Absolutely.
So, until the next time, it's goodbye from George. Goodbye. And it's goodbye from me. Goodbye.