You always hear that skin is your largest organ. Honestly, I would say that few of us really think of it as organ. Yes, it’s the covering of your body that you see when you look in the mirror.
But it’s so much more.
As Monty Lyman says in his wonderful book, The Remarkable Life of the Skin:
“From survival to social communication, your skin is the Swiss Army knife of organs-it possesses a variety of functions unmatched by any other.”
Your skin both protects and connects you with the outside world. It has social, psychological, spiritual, and physical functions. Your skin:
- Controls water balance (so you don’t dry up or become water logged)
- Maintains your body temperature by sweating or closing up your pores
- Guards against invasion by microbes and foreign matter (both physically and through the acid mantle)
- Protects your internal organs from the outside world
- Connects you to the outside world through your sense of touch, pressure, hot, cold,and more
- Starts the process of vitamin D production by absorbing UVB rays
Lucky for us, it’s an organ that we can take care of directly.
Your skin is two distinct layers, the epidermis and the dermis. There’s a third deeper layer called the hypodermis which acts as padding and helps with temperature regulation.
Your epidermis is your outer layer, also known as your skin barrier. It’s only about 1mm thick and serves as the wall between you and the outside world.
Your epidermis has no blood supply.
It’s stretched, scratched, and squished a thousand times a day, but it doesn’t break (not easily anyway) or wear out.1
It’s battered by UV radiation from the sun but it keeps it from ever touching your internal organs.1
It’s constantly exposed to all kinds of deadly bacteria and microbes, but they rarely get through to wage war in your body.
So, yes, your skin barrier really is like a brick wall. The cells are like bricks and the matrix of fats.
The cells in your epidermis start as live cells in the basal layer of your epidermis. The main protein in your epidermis is keratin. Keratin is unbelievably strong. It’s what horns of rhinos and your own hair are made of.
These new cells move up towards the surface of your skin over the course of a month (longer as you get older). As they do they make the mixture of fats that become the mortar of the outer brick wall.
They also flatten out and eventually die. They become hard. Interlocking plates of keratin (the bricks) surrounded by the fatty mortar they’ve made. This produces a waterproof surface that keeps you from absorbing water when you get wet or take a shower and swelling up like a sponge.
At the end of their (approximately) month long life, the dead cells flake off (or are exfoliated off). Believe it or not, you shed more than a million skin cells a day.
These shed skin cells make up about half the dust you find in your home. 1
But not to worry. New keratinocytes move up to take their place and keep you and your body safe and protected. Your entire skin barrier is completely replaced each month without ever exposing you to leaks or breaks.
It goes without saying that keeping your skin barrier in good shape is critical to your health (and beauty).
Your dermis is the layer beneath your skin barrier. It makes up most of your skin’s thickness.
Monty Lyman likens your epidermis to a factory roof and your dermis to the bustling workshop under it.1
Your dermis contains nerves, blood and lymph vessels.
It contains the fibroblasts that produce collagen which gives your skin its strength, firmness and plumpness. And elastin which allows your skin to stretch and bounce back.
In between the fibroblasts, there’s a gel like matrix of important molecules like hyaluronic acid that help with tissue repair and support both your dermis and epidermis with nutrients.
The dermis is also where your sweat glands, sebaceous (oil) glands, some of your skin’s immune cells, and hair follicles are located.
Hypodermis and Cellulite
Beneath your dermis is a fatty layer known as your hypodermis. Your hypodermis has a rich blood supply. It’s main function is padding and insulation.
Whether it’s an actual part of your skin is a matter of controversy. I only mention it here because I though you might be interested in cellulite.
Cellulite is a natural occurrence in almost all post adolescent women (90%) and only about 10% of men.
It may seem unfair, but it’s part of the way we women are put together.
The fat in your hypodermis is kept in place by collagen fibers that run from the dermis down through the hypodermis and to the tissue and muscle below.
In women, the collagen fibers are arranged in parallel columns while in men it’s in a crisscross pattern. When hormones, genetics, and age intervene, the fat cells of the hypodermis can push up through the space between the parallel columns and into the dermis. The result is cellulite.
In men, the crisscrossed fibers keep the fat cells in place.
Knowing about your skin helps you take better care of it
We can use our existing knowledge of how skin is structured and how your skin absorbs ingredients to get better results from skin care products.
Your skin cells themselves are mostly water and protein. To affect them, you need water based products.
Effective serums are designed to deliver a high concentration of active ingredients into the deeper layers of your epidermis and hopefully upper layers of your dermis to nourish and encourage them.
This is why most serums and active ingredients are water based with perhaps a small oil based component. Even then, getting serums and active ingredients to go deep enough into your skin to have an effect is difficult. You need to be sure the actives are small enough (under 500 daltons), and take in to account a myriad of other factors to penetrate that brick wall.
On the other hand, the “mortar” between your skin cells ( in your epidermis) is oil based. That means that oil and butters can penetrate and be absorbed through this matrix.
So when you’re trying to seal in moisture and protect your skin barrier, you need to have some oil/fat based ingredients to help seal the “mortar”.
And with moisturizers, it’s a balance.
You may have noticed that if you have dry or dehydrated skin, using a facial oil alone often won’t make your skin feel moist.
This is because oils help the mortar between your skin cells but aren’t well absorbed into cells themselves, which are mostly water.
A better approach is to harness the powers of both water and oil based ingredients using a moisturizer. Moisturizers are typically emulsions. Emulsions contain both water and oil based ingredients bound together with an emulsifier. The oils seal up cracks in your mortar and the water based ingredients go to work on your skin cells.
Once your skin is hydrated, you can use a light layer of facial oil to seal in your skin’s hydration and deliver additional nutrients. The oil will actually be more effective this way.
- Lyman, Monty. The Remarkable Life of the Skin. Atlantic Monthly Press, 2019.