Skin Anatomy
Your skin, the largest organ of your body, must be supplemented and protected. Healthy, beautiful skin is determined by its structure and proper functioning of the components within. Before you can understand your beauty products, how they may benefit you and the ingredients they contain, you must first have a basic knowledge of your skins anatomy and how it functions.
Skin is composed of many layers but is broken down into three main categories. First the Epidermis; the top layer of skin which acts as a protective shield for your body. Second is the Dermis; the Dermis provides structure, elasticity and support. Lastly the hypodermis, often called the Subcutaneous layer, this layer is the fatty tissue that provides padding and insulation for your body.
Epidermis
The Epidermis is the outermost top layer of our skin and is categorized into five horizontal layers. It has the thickness of a sheet of paper and completely renews itself with fresh skin cells every 28 days! It functions as the protective shield for your body. The five horizontal layers are:
1) Stratum Basale:
This is the deepest layer of the Epidermis. It is composed of a single layer of cube shaped cells; the bulk of the cells being Keratinocytes and Melanocytes.
Keratinocytes are new skin cells which are formed in this layer, they work their way up through the layers and replace those shed from the upper layer of the Epidermis; this process is called Skin Cell Renewal. As we age, the rate of cell renewal decreases.
Melanocytes are our pigment cells that produce Melanin (skin pigment). Melanocytes transfer pigment to the nearby Keratinocytes (new skin cells) which will eventually work their way to the skin’s surface. Melanin is photoprotective and helps protect our skin from ultraviolet radiation (sun exposure)
2) Stratum Spinosum
The Stratum Spinosum is the second deepest layer of the Epidermis and often called the prickle cell layer. This is the layer where the Keratinocyte cells change from cube to polygonal shape and start to synthesize Keratin, the tough, fibrous structural protein which gives our skin its protective properties.
3) Stratum Granulosum
Stratum Granulosum or the Granular layer is made up of 3-5 layers of flattened Keratin. This is the layer where the major activity begins as water-proofing lipids and Keratin proteins are produced and organized.
4) Stratum Lucidium
The fourth layer of the Epidermis is nicknamed the “clear layer”. Present in thick skin, this layer is only found in your fingertips, palms of the hand and soles of our feet. It helps to reduce friction and forces.
5) Stratum Corneum
Stratum Corneum or the Horney layer is the very top layer of the Epidermis. This important layer is responsible for maintaining the skin’s hydration and integrity, it is the actual protective layer of our skin. With complex processes at work, even minimal disruption can cause a variety of skin problems including dryness, itching, redness and others skin issues.
The Stratum Corneum is a combination of Keratinocytes and lipids stacked in a brick and mortar like pattern. The flattened Keratin cells being the bricks and the Epidermal lipids acting as mortar. The Epidermal lipid cells consist of ceramides, fatty acids and lipids.
The Keratin blocks provide strength yet allows the absorption of water. The combination of Keratinocytes and lipids in a brick like pattern forms a waterproof moisture barrier which keeps moisture in and minimizes trans epidermal water loss (TEWL). This moisture barrier also protects against invading organisms, chemical irritants, allergens and other skin concerns.
Dermis
The Dermis is located between the Hypodermis and the Epidermis. It is categorized into two different layers, the Stratum Papillare and Stratum Reticulare. The lower layer, Stratum Reticulare, makes up most of the Dermis. This is a fibrous network of tissue that gives the skin its structure and elasticity. Its thickness can vary, but on average it is just slightly thicker than a penny!
The major components of the dermis work together in a mesh like network. This network is composed of collagen (strength), elastin (elasticity), blood/ lymph vessels and specialized cells called fibroblasts and mast cells. The network is surrounded by a gel-like substance called ground substance, which is made mostly from glycosaminoglycans. Glycosaminoglycans are composed of hyaluronan, glycoproteins and proteoglycans. This gel substance plays a key role in hydration and moisture levels in the skin.
The main structural component in the dermis is the protein collagen. This mesh- like network gives the skin its strength and flexibility. The Glycosaminoglycans are moisture binding molecules that enable the collagen fibers to retain water and provide moisture to the Epidermis. Also found in the dermis is a coil shaped protein named elastin, this gives the skin its elasticity by allowing it to return to its original shape after stretching.
Both collagen and elastin are produced in specialized cell called Fibroblasts, which are located mostly in the upper edge bordering the dermis.
Throughout the Dermis are blood vessels, lymph vessels, nerves and mast cells. Mast cells are specialized cells that trigger the skins inflammatory response to physical injury, allergens and microorganisms.
The blood vessels in the Dermis help regulate and release heat, they also aid in providing oxygen and nutrients to the lower layers of the Epidermis. This nourishment only reaches the bottom layers of the Epidermis, the cells in the top layers are dead because they do not receive oxygen or nutrients.
The top layer of the Epidermis, Stratum Papillare, is a wave like border that provides increased surface area so that oxygen and nutrients can be easily exchanged to the Epidermis. Along this junction are finger like projections called Dermal Papillae. As you age, the dermal papillae flatten, decreasing the flow of oxygen and nutrients to the epidermis
Hypodermis
The hypodermis is the deepest, bottom layer of skin. It is composed of fatty tissue which insulates the body from cold and shock. The fat cells also store energy and nutrients. The hypodermis is thickest in the soles of the feet, palms of our hands and buttocks. As we age, the hypodermis begins to decrease, contributing to the thinning of aged skin.
Knowing how your skin works will give you a greater understanding on how to care for your skin, the products you use and what the individual ingredients may offer you.
cosmotruth 