This article was written by Vitaly Solomonov
In this article, we take a short trip deep in our skin in order to understand clearly how the skin works and protects the inner environment of our body. Understanding the skin structure and the epidermal structure in particular answers the questions what the skin really needs and why.
Human Skin and cosmetics
The human skin is a unique protective tool and very strong border between our body and external world. We know almost everything about its structure, but rarely realize the real functionality of its parts and layers in terms of Cosmetic Science. The common skin schemes tell almost nothing, but showing us the layers and vital parts of the skin. All three main layers of the skin have different anatomy, but created in order to perform one important task – together, they protect us from severe impact of external world. Well, let’s see…
This is the deepest layer and built almost completely with lipid cells. When we are on a diet, we are fighting with this layer. The Hypodermis is a depot of very nutritive substances and energy. Every spare minute our organism is trying to hold over the excessive fat in the Hypodermis in order to be ready in times of famine. During starvation or shortage of nutrients, the fat from the Hypodermis decomposes chemically into water and energy. I won’t go into this layer in detail since we will discover more interesting things within the upper skin structures for cosmetic chemists.
It’s the heart of the skin and it’s a vivid part that impacts all skin functions. If we look at it closely, we find it has a gel structure. This gel almost completely built with two types of proteins – Collagen and Elastin. The fibers of those proteins intertwine like bedsprings in matrasses. With the certain amount of water, the protein fibers form the gel. The dermal water is coming from the blood stream constantly and constantly the blood stream picks up the waste of skin and brings them to the liver. However, the skin tries to retain the water, since it’s the most important ingredient for all it’s functions.
Natural Moisturizing Factor
Hyaluronic acid, urea, Lactic acid and some other substances help the main proteins to keep water in the Dermis. The mix of such hygroscopic molecules that able to keep a lot of water is called The Natural Moisturizing Factor of the skin (NMF). The general rule for cosmetologists and cosmetic chemists: More water – the better skin condition. While the NMF determines the amount of water in the skin, another factors defines water loss. The rate of water loss is the most important factor for the skin and it could be measured with the special instruments during experiments or testing the new cosmetic products. The human skin loses the water when it damaged or inflamed or aged.
Unfortunately, the skin loses ability to keep the water during aging. The main role in it plays Collagen since it’s fibers are getting unable to retain the water to keep the “skin gel” in shape. The Collagen fibers become destroyed and protein structure is changing significantly. Old and damaged Collagen doesn’t form gel structure efficiently anymore and we could observe the signs of skin age, the skin loses the tension and the force of gravity has a greater impact on wrinkle formation with skin sagging.
The amount of water is important for all Dermis’ function. While the NMF and function of bloodstream maintain the volume of water, Trans Epidermal Water Loss (TEWL) regulates the water release through the evaporation. The dermis also contains nerves and nerve endings, blood vessels, immune and pigment cells, hair follicles, sweat and sebaceous glands. All those structures act as entire system in order to maintain the constant protection for our body.
This is the terminal part or outer layer of the skin and its Micro Anatomy differs from Hypodermis and Dermis. The Dermis and Epidermis are divided by a basal membrane. The basal membrane is the base for all the epidermis layers of cells. The Water, Oxygen and all other nutrients diffuse through this membrane to nourish epidermis cells. The epidermis contains no blood vessels, thus the function of the membrane is so important for all epidermal cells, especially for basal cells or basal Keratinocytes. Melanocytes are also found at this basal layer – they are the cells that produce Melanin which protects us from all types of UV rays. This is the first layer and the most important one. Keratinocytes are constantly dividing. One part of the divided basal cell remains stuck to the basal membrane and another part is squeezing up to the next raw where the process of cell aging begins. This young cell should cross the entire epidermis and reach its top.
The rest of the epidermis’s thickness is divided into another four layers: spinous, granular, clear and the final cornified layer. In fact, every epidermal layer is a stage of the keratinocytes’ life. We can discover some very interesting chemical conversions in the cells within these layers. From one cell raw to another, the constant transition of the keratinocytes to the top of the skin surface leads to their death within the cornified layer. Yes, it is probably sad to say, but being born in the basal layer, the cell is striving eventually to die to perform the main task of its life – to ensure the protection and strong security for our body and all living cells and tissues. Those small kamikazes are born to die. Mother Nature has created unique and genius device protecting us from highly inhospitable environment. Indeed, the best decision is to protect the living tissues with some non-living substance. In our case – dead cells of the epidermis.