My love affair with skin care started at age 11, when puberty, eczema and the Mombasa heat nearly did me in. I came across one of my sibling’s books, a biology book to be exact; it changed everything. After learning the structure of the skin and watching Renchia Droganis of Africology on CNN, this #BrainyBeauty was born.
The way I see it, we can’t possibly address the needs of our skin if we don’t understand its basics. Understanding the structure of our skin and how it works will help us maintain its health, so can we agree that Skin 101 is a no brainer? Yep. I thought so. Why don’t we figuratively whip out that biology book?
Let’s start from the beginning, refresh our knowledge of the structure of the skin, hairy pic (forgive me) and all!
Skin 101: The Structure of the Skin
The skin is the largest organ of the body. This title comes with a lot of responsibility. Loaded with sensory receptors that send signals like pain to the brain, the skin also helps maintain a constant body temperature while providing a physical barrier to the environment
(which is a whirlwind of microbes, chemicals and ultraviolet light). All while carrying out the most important function of all, creating a barrier to water loss.
The skin is composed of three layers:
- Subcutaneous layer
This is the tough outer layer of the skin. It has multiple layers:
- Stratum corneum; It’s comprised of approximately 20 layers of corneocytes – dead skin cells comprised primarily of a structural protein called keratin. These cells contain water-soluble compounds known as Natural Moisturizing Factor (NMF) which maintain hydration. The corneocytes are surrounded by a fatty lipid layer making the skin relatively waterproof and when undamaged, it prevents most bacteria, viruses and other foreign substances from entering the body. Sometimes the stratum corneum is referred to as the moisture barrier or lipid barrier. The outermost layers of our moisture barrier have an acidic pH that can range from 4.0-6.0, with the average being 4.7. The acidic layers are often referred to as the “acid mantle,” which plays an extremely important role in the condition of our skin. The acid mantle’s low pH stops the growth of pathogens and maintains the durability and structural integrity of the keratin proteins in our keratinocytes. Those with a pH on the lower end of the 4.0-6.0 scale have greater overall skin health.
- Stratum granulosum: This layer has active cells which produce the lipids that are released into the stratum corneum. The most common lipids are ceramides, free fatty acids and cholesterol. This is also where keratinocytes are transformed into corneocytes. The resultant corneocyte is comprised of about 80% keratin by dry weight.
- Stratum spinosum: Here, column shaped keratinocytes from the basal layer become polygonal and produce keratin – a key structural protein in hair, skin and nails.
- Stratum basale (Basal layer): The deepest layer of the epidermis has a single row of cells that divide to form new keratinocytes which slowly migrate to the surface of the epidermis. Once they reach the skin surface, they are gradually shed and are replaced by newer cells pushed up from this layer. Scattered throughout the basal layer of the epidermis are cells called melanocytes, which produce the pigment melanin, one of the main contributors to skin color. Melanin’s primary function, however, is to filter out ultraviolet radiation from sunlight. Sunburn and a higher risk of skin cancer are some of the effects of over exposure to UV radiation.
This is the thickest layer of the skin where synthesis of elastin, fibrillin and collagen protein occurs. These tissue proteins are responsible for the elasticity, flexibility and strength of the skin. The dermis contains nerve endings, sweat glands and oil (sebaceous) glands, hair follicles and blood vessels.
Subcutaneous Layer/Fat Layer/Hypodermis
This is a layer of fat that helps insulate the body from heat and cold, provides protective padding and serves as an energy storage area.The fat is contained in fat cells, held together by fibrous tissue.
As always (especially in this month of love when smooth skin is a priority, ahem!),