Skin 101 - Everything you need to know about your biggest (and most noticeable!) organ PART I: The Epidermis

July 13, 2015

Skin 101

Our largest organ is often erroneously thought of as one “thing.” In reality, it’s more like a kingdom with 50 different duchies.   If skin were a person, it would have multiple personality disorder.   Looked at from the surface, over here you’ve got craggy, parched cliffs scoured by sun and sand.  One region is oily with crevasse-sized pores; right next-door it’s flaky, thin, and dry.   And that’s just the surface.  Above as below, skin is a complex, corrugated layering of tissue, cells, glands and other biological components, each vital to the health of the entire organ.   It protects us from damage and pathogens both internally and from the outside environment.  Skin is a storage center for lipids and water, a semi-impermeable barrier to fluid loss so essential nutrients aren’t washed out of our bodies.  We have three principal layers: The Epidermis, the Dermis, and the Hypodermis.  The relative inconsistency of these layers explains, in part, why we end up with irregularities in color, tone, and texture. 

 

The Epidermis:  Outermost Waterproof Barrier

 

The epidermis is the outside surface of skin that we can see.  It is the waterproof barrier intended to separate us from the external environment, i.e. toxins, pollutants, and infection, and to keep the good stuff in, things like blood, fluids, bones, and tissues.   Made up of epithelial tissue consisting of four types of cells, it is quite thin, about ~ .1 mm, or the thickness of a sheet of paper.  Because of its ingenious design, very little can penetrate the epidermis.   This is your first clue to why so many products don’t seem to have any measurable effect. 

 

When we say “skin,” most of us are referring to our epidermis, and more specifically the outermost layer of the epidermis, or stratum corneum.  Composed entirely of dead skin cells, It takes anywhere from two weeks to a month for living cells to migrate from the lowest layer of the epidermis to the uppermost stratum corneum, where they die and slough off.  This process of skin cell renewal slows down as we age.  Beginning somewhere in our 40’s, women experience dramatic hormone decline as we approach perimenopause.   The epidermis thickens, making skin look dull.  Lubricating, refining, and plumping the stratum corneum so that it looks dewy is the temporary function of the vast majority of skin care and moisturizing products.

 

Important Skin Fact:  THE PART OF OUR SKIN THAT WE CAN SEE IS MADE UP EXCLUSIVELY OF DEAD SKIN CELLS.  

 

Not living.  Dead as a doornail.  Kaput.  And there’s nothing you can do to reanimate them.  It is not living tissue, and yet we mistakenly emphasize – and spend the most money on – those dead layers of skin.  On the other hand, we can’t ignore those dearly departed, flattened cells.  But we can grease them up so that they look alive.  In fact, they demand to be plumped up at regular intervals, or else.  Demoralized yet?  Take heart.  While pampering the epidermis is literally a superficial activity, it has an immediate and noticeable effect.  To assure skin’s long-term health, however, we must attend to the deeper, unseen layers, which are unreachable by even the most assiduous typical daily devotions.  

 

Important Skin Fact:  YOUR EPIDERMIS IS LIPOPHILIC

 

The epidermis is lipophilic, meaning it is fat loving, and hydrophobic, or water fearing.   Why does this matter, you ask?   Our epidermis, for the most part, can’t absorb water.  It repels it, like the glistening hide of a baby sea otter.  Well not exactly, but it’s a fact that too much water strips away our natural oils, leaving skin unprotected, dry, and disastrously wrinkle-prone.  If you’re 18 and acne-ridden, maybe losing some of your skin’s corporeal lube doesn’t seem so dire.  But when it comes to aging skin, we must jealously guard that precious fatty sebum.  The epidermis needs oil.   And because it is a lipophilic membrane, it will readily accept fatty compounds.  Not only does it need oil, it responds to it in ways that might surprise you.  For example, oil application actually lessens oil production.  Oil also dissolves excess oil and other impurities that have surfaced, without stripping the intrinsic protective layer, making it a superior cleanser.   

 

Our epidermis also needs water, fresh, pure, warm (or room temperature) water, but oil must be present along with it to trap and hold that moisture.  It’s a commonly held belief that hot water is bad for skin, but a nice splash of cold water enlivens it.  This is utter nonsense!  ALL water dries skin, though hot more than cold.  A cool spritz can temporarily constrict blood flow, giving a momentary appearance of freshness, but it does not shrink pores and it does, in fact, dry skin.  Hot water will soften sebum and carry it away like a leaf on water, and will irritate it to boot.  Under most circumstances, we want to keep our epidermis and water at arm’s length, though the deeper layers of skin are happiest when they are watered (from the inside out).

 

Acid Mantle

Not technically part of the skin but crucial to skin’s health is the acid mantle, an acidic layer of sebaceous and sweat glands sitting atop the stratum corneum and forming another protective barrier against pathogens.  It’s like the ozone of skin: when it gets ripped apart, all kinds of bad stuff can get in and things get ugly underneath.  The acid mantle can easily be stripped and thereby weakened by use of detergent-laden cleansers, scrubbing, or over-exfoliating. 

 

In the alimentary canal we shoot for alkalinity, but on the skin’s surface we aim for a slightly acidic pH.  Acidity not only protects against harmful bacteria, but also helps maintain the hardness of keratin proteins.   When the pH of the acid mantle is disrupted (becomes alkaline), our skin becomes prone to roughness, dehydration, and, heaven help us, premature aging.  I know what you are thinking.  You are thinking, Why, I would never in a million years put an inferior product on my skin! Unfortunately, even what appear to be the best quality cosmetic brands, purchased in shishi department stores, end up high on the alkaline meter, destroying the acid mantle with no ancillary benefit (such as exfoliation).  Even the purest water is alkalizing on its own, as it has a higher pH than skin.  

 

Next post:  Skin 101, PART II:  The Dermis (muy importante!)

 

 

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