How our skin functions

Acid Mantle Barrier Function cosmetic chemistry Dermis Epidermis skin TEWL

Let's talk about our largest organ. THE SKIN! 

Fun facts:

  • The skin is part of the integumentary system which comprises the hair, skin, nails, specialized glands and nerves.

  • The skin is the largest and heaviest organ- it comprises 16% of your bodies weight, (bonus fact- the liver is the second largest and heaviest).

  • The skin is a barrier, a thermostat, a sensor, a factory and a window.

  • The skin can be broken down into 3 major layers with minor layers living within those layers

    • the epidermis, dermis and hypodermis

      • The epidermis has 5 layers (stratum corneum is the top most layer with stratum lucidum, stratum granulosum, stratum spinosum and stratum basale following deeper and deeper.)

      • The dermis has 2 layers and it's main job is to connect the epidermis to the hypodermis and provide structure and support (papillary layer and connective tissue are it's 2 layers)

      • The hypodermis has one layer it's job is to provide insulation and support.


Alright- let's break this all down! I am going to focus on the epidermis because that is the part that is most directly affected by skin care products.



The skin is a barrier. I am going to repeat this THE SKIN IS A BARRIER, it is NOT a sponge. Every time I see someone write this on FB or say it I die a little bit on the inside. If the skin were a sponge we would drown every time we took a shower or bath. 



The skin is a waterproof barrier that seals the body from losses of fluid that could lead to dehydration and death. It resists invasions by various types of microorganisms such as bacteria, fungi and viruses that cause infection and serious illness. The skin also blocks many chemicals and allergens from entering the body.



The skin is a thermostat. The skin has the ability to help cool you down or keep you warm, it works in conjunction with the blood vessels to do this. 



The skin is a sensor. It has millions of receptors and nerve endings. There are different types of receptors which perceive different stimuli.



The skin is a factory. The skin is the body's vitamin D production factory. We need vitamin D to build healthy bones a strong immune system which will in turn fight cancers and other diseases as well as mitigate depression and even multiple sclerosis.



The skin is a window. How you feel inside directly affects how your skin can look. If you are happy and healthy and internally balanced it will be reflected in your skin. If you are stressed, anxious, depressed or have some internal health issues it can be reflected by way of skin flare-ups, disease processes, brittle nails and hair. People with eczema and psoriasis tend to have flare-ups when they are stressed or having diet issues.* 



Let's talk epidermal layers!



Stratum corneum- contains 15-20 layers of dead skin cells that ultimately slough off.



Stratum lucidum- this layer is mainly found on thick skin like the palms of the hands and soles of feet, it contains dead keratinocytes.



Stratum granulosum- keratin and lipids that waterproof the skin are produced in this layer



Stratum spinosum- synthesis of keratin proteins begins in this layer



Stratum basale- the cells of this layer divide indefinitely to form daughter cells that rise through the epidermis. Basal cell cancers arise from this level.



Skin and skin care products. Some ingredients can absorb into the deeper layers of the epidermis, these are called active ingredients. Cosmetic chemists often talk about the penetration abilities of ingredients. This is what they are referring to. 



Other ingredients can absorb even deeper, sometimes because of the penetrative abilities and what they can accomplish on a deeper level these products fall into the category of being a drug and must be tested and approved through the FDA, by the way, sunscreen falls into this category, never buy sunscreen that is not FDA approved, you have no idea if it will actually provide the protection that it claims otherwise. On a side note, at this time, there is only one approved CBD topical that has been proven to penetrate deeply and be effective for bone and joint pain. Consider this if you are in the market for a CBD topical that you want to penetrate deeply. 



Some products sit on top of the skin and work their magic at that level, many handcrafted skin care items fall into this category. (some makers do use active ingredients and have products that penetrate deeper.) At the time of writing this post SOAPSMITHS products do not contain any actives nor do they fall into the category of a drug. 


Hard Cider Soap by Soapsmiths


When formulating products I take into consideration what I am trying to achieve. If I am making soap I need it to clean. THAT IS IT! If someone gives you a song and dance about other properties their soap has just smile and nod because you now know that it only cleans and as a wash off product it most likely does nothing else. The second someone claims any differently their soap becomes either a cosmetic or a drug and they could be up a creek without a paddle if the government folks catch wind of it.



When formulating a scrub I want it to exfoliate those dead Stratum corneum cells so that the lotion that I will apply after can hydrate and protect the layers of skin that were under them.












When creating a lotion I want it to hydrate and protect. The best way to do this is to use a combination of oils and waxes which will both sit on top of the skin forming an occlusive barrier while also hydrating those top most layers. A product like a lotion is really the place to add special ingredients which may improve skin barrier function. The only way to really know would be to submit it for testing. Most small makers don't have the financial means to do this so we take our ingredient and formulating knowledge and build a product based on what we know. 






So there you have it. The skin is an amazing giant organ which keeps good things (like our organs and fluids) in and bad things (bacteria, yeast, fungi, etc.) out! Treat it well and you two should have a long and prosperous life together.



TED talk link all about the skin.



I also referred to the Reader's Digest Guide to Skin Care by Susan C. Taylor, M.D. and Victoria Holloway Barbosa, M.D.



Additionally I popped over to a blog called the Chemists Corner for information on the penetration of ingredients.



* Regarding my comment on eczema and psoriasis, if you are having trouble with skin conditions please seek professional medical advice, I am not trained in human medicine and do not make any claims or diagnoses with what I write.



~Yours in scientific musings




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