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The Epidermis and its Role in Skin Health

The epidermis is the outermost layer of your skin.

It is a waterproof, protective barrier and plays a critical role in skin rejuvenation.

The epidermis was once considered a superficial shell, but discoveries about the psychological processes in our skin, have found it to be so much more.

Many changes occur deep within this layer; changes which are due to ageing, stress, UV, environmental pollutants and chemicals, and poor lifestyle habits such as smoking and drinking.

What is the epidermis?

The prime function of the epidermis is to act as a physical and biological barrier to the external world, preventing penetration by irritants and potential allergens; at the same time, it prevents the loss of water and maintains your internal homeostasis.

New cells are made in the lower layers of the epidermis, and over the course of around 4 weeks, these cells make their way to the surface, where they become flat and hard, replacing dead cells; literally, millions of these skin cells are shed daily.

Keratinocytes are the most common cell type within the epidermis; their job is to act as a barrier against bacteria, parasites, fungi, viruses, heat, ultraviolet (UV) rays from the sun, and water loss.

The colour of your skin is produced by a pigment called melanin, which is produced by melanocytes; these are also found in the epidermis and help to protect your skin from UV rays.

Interestingly, the epidermis contains no blood supply of its own, which is why you can shave your skin and not cause any bleeding, despite losing many cells in the process.

The epidermis is composed of five layers

  • stratum corneum is the outermost layer
  • stratum lucidum
  • stratum granulosum
  • stratum spinosum
  • stratum germinativum

The epidermis and its role in skin health

The keratinocyte cells are created at the junction, between the epidermis and the dermis. When they are ready, they begin a month-long journey towards the top of the epidermis, the outermost layer of your skin referred to as the stratum corneum.

When they begin their journey, they are plump and healthy, but as the keratinocyte cells begin to move towards the surface, they break down, becoming flat and hard, where they fill with a tough protein known as keratin.

This protein gives your skin it’s waterproof covering, protecting you from the outside world, preventing the absorption of many substances through your skin and potential viruses and bacteria.

Once at the surface, they start to shed; this is a continuous cycle as new cells move towards the surface. Whilst 95% of these cells are there to make way for new cells; there are around 5% that contain melanin which helps to determine our colour, the darker the skin, the more of these cells there are.


So as we can see, the epidermis is the outermost layer of your skin, which serves as a physical barrier, protecting your body against external aggressions such as cold temperatures, UV and bacteria. The rest of the epidermis mostly serves the role of producing the skin barrier.

A little known fact is that the interaction between cells in the epidermis and cells in the dermis is so strong, that cells within the dermis actually influence the way the epidermis functions, this regulates its ability to create healthy new cells and clearer skin.

This article, a guide to the physiology of the layers of the skin, contains some interesting facts on the epidermis.

4 thoughts on “The Epidermis and its Role in Skin Health

  1. Robin says:

    Thanks so much, Samantha, for your helpful response. It seems that you advise against using Vit C serum. Does your advice apply only after dermarolling, or do you think it should be avoided under all circumstances? Some say that Vit C is effective on dark spots, and I have age spots on which I would like to try it. Many thanks! Robin

    • Verified Author Samantha Miller replied:

      Hi Robin
      Vitamin C should only be avoided after microneedling or other treatments that disrupt the barrier other than that it will be great for brightening and lightening. watch this space for our anti pigment paste coming in the next month or so with vitamin C.

  2. Robin says:

    Dear Samantha,

    So glad to read your sane and scientifically grounded advice. Someone highly recommended dermarolling and I tried it at home. I’m 56 years old, and have many acne scars from my youth. I used .25mm for about 3 months 2 or 3 times a week and then applied Vit C serum right afterwards. I thought it was improving my old scars slightly. Still, I just felt weird about the redness and slight pain I experience afterwards and looked up info on long term side-effects, which led me to your webpage. I’m going to stop doing it now, but I wonder what the long term impact of the damage to my skin would be like going forward. Has the 3 months worth of dermarolling done irreparable damage or would leaving my skin alone help restoring its health? Would the premature aging occur in the next few years? How do I prevent it? Thanks! Robin

    • Verified Author Samantha Miller replied:

      Hi Robin. At this stage I am so glad you have stopped the micro-needling, Robin what we know is that for some reason, some people have adverse reactions to this treatment, quite why – well there are a number of reasons to many to mention. here, and this also goes for the results, everyone heals differently, but your skin should slowly heal, just pull back on everything topical less is more, don’t fall into the trap of adding actives especially vitamin C and having aggressive peels etc to try to repair the damage you need your barrier to heal. After 3 months of this treatment, you should know that there are a few stages after treatments that cause injury and in the first stage, the damage is happening anywhere between for 0-6 months but can last up to 8 months. so give your skin time to heal. Samantha

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