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Skinformation: How Skin Biology Helps You Choose Better Skincare

Our skin is the largest organ in the body. Period. It’s complex, and it deserves respect. To understand how your skincare products work, it helps to have a basic understanding of what goes on beneath your skin.

Now we’re not asking you to take an anatomy course (although as a student esthetician you will learn a ton about the human body!).

But no doubt about it, when you understand the basics of how your skin works, you’re better able to interpret the claims that skincare companies make about their products – what’s true, somewhat true, what’s totally false, what’s pretty near impossible and everything in between. And that translates into better skin health for you and better financial choices for your wallet when considering what products to purchase for your homecare.

So, here’s a simple explanation of what and how that beautiful skin you’re in protects and defends you every day – stick with us, you’ll learn something!

As mentioned above, the skin is the body’s largest organ. It’s composed of seven layers, which all have very specific functions. Your skin is actually part of your body’s immune system and is a first line of defense against bacteria, germs, damaging UV rays, chemicals, and injury (wounds). It helps you maintain your body temperature and prevents excessive moisture loss.


We start with the epidermis, where the first 5 “layers” are located (The dermis is composed of the next 2 layers.)

The epidermis is the outer layer of skin that protects the body from infections, dehydration, and injury. It also renews cells in the skin. This is the part that’s visible. The epidermis is constantly renewing and regenerating, with new cells made in the lowest layer (basal cells) that eventually push their way to the top. This process takes about 28-30 days but slows down as we age. Which means that cleansing and exfoliating the skin becomes even more important as you get older. Cell buildup is one cause of skin looking dull and lacking vitality and freshness.

The layers of the epidermis from the surface (outermost) layer and working our way to the deepest layer are as follows:

1. Stratum corneum

· The first line of defense against environmental stressors, bacteria, UV damage, wounds/injuries.

· Helps prevent TEWL (trans-epidermal water loss) which means preventing moisture loss, dehydration.

· This layer is made of 10 to 30 thin layers of continually shedding, dead skin cells (keratinocytes).

2. Stratum lucidum

· A thin, clear layer found in skin prone to damage – palms of the hands, and soles of the feet. (2-3 cells thick).

· Its function is to help the body lower the effects of friction and is responsible for the capability of the skin to stretch.

3. Stratum granulosum

· The layer that functions to keep the body from moisture loss. 1-2 cells thick.

· The fats contained in this layer help keep skin cells attached to each other.

· It’s composed of keratinocytes that have matured to where they are beginning to produce the large amounts of keratin (protein that helps form the tissues of hair, nails, and outer layer of the skin) that will eventually fill the cells.

4. Stratum spinosum

· This layer is about 8-10 cells thick and is known as the “prickle cell” layer due to their spiny appearance.

· The cells here are part of the immune system help to fight against germs

· Provides a continuous netlike layer of protection to withstand effects of friction and abrasion.

5. Stratum basale (germinativum)

· The deepest layer of the epidermis (aka, stratum germinativum or "germinate").

· Cell division (mitosis) occurs here, “germinating” and creating new cells.

· These cells produce keratinocytes containing protein, fats, and help the body produce Vitamin D when exposed to sunlight.

· Melanocytes are contained in this layer which produce melanin which determines skin color.

Note: Over the counter skincare products ONLY treat the outer layer of the skin (epidermis)


The dermis is the layer beneath the epidermis that contains blood vessels, nerve endings, hair follicles, and sweat glands. The dermis functions to provide elasticity, firmness, and strength to the skin. When we’re young, the dermis is loaded with collagen and elastin which gives skin that “bounce” and shape. As we age, these fibers break down faster than our cells can replace them, which leads to wrinkles and dry skin.

The dermis is made up of 2 layers:

1. Papillary Layer

· This thinner upper layer of the dermis connects the dermis to the epidermis.

· It is full of capillaries that bring nutrients to the skin and increase/decrease blood flow to help regulate body temperature. Looser connective tissue, highly vascular.

· Contains sensory neurons that give us the sense of heat, cold, pain, pressure, etc.

· Contains thin collagen fibers.

· It is the layer of the skin responsible for fingerprints.

2. Reticular Layer

· Deeper, thicker layer of the dermis composed of dense connective tissue.

· This contains our hair follicles, sweat glands, and oil-producing glands (sebaceous glands), as well as the beginning of pores, which push hair, sweat and oil to the surface.

· Contains thicker collagen fibers.

· Its function is to strengthen the skin and provide its elasticity.


Lastly, the layer of skin right underneath the dermis is called the subcutaneous layer or hypodermis. This layer provides insulation for your body, keeping you warm. It also provides a cushion to protect against impact surrounding your vital organs.

The subcutaneous tissue tends to thin as we age, and when this happens our skin looks less smooth, and the underlying veins show through. It can also show up as cellulite in other areas of the body.

Knowing how your skin does what it does helps you become a more educated product consumer – there are a lot of benefits!

  • You understand and learn how to target visible signs of aging, enlarged pores, breakouts, and other skin conditions.

  • You are tuned in to protecting your skin from harmful sun damage.

  • You realize that as we age, the skin naturally loses elasticity, firmness, and tone. Proper skin care can restore firmness and even texture to the skin.

  • You can recognize when a skincare company’s claim has merits or when it sounds just too good to be true, based on your knowledge of how our skin works.

Think becoming a skincare specialist might be in your future? Contact Admissions and come visit us! Visit our Course Page to see what you could be learning!


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