The skin is a vital organ covering the entire outside of the body thereby protecting it against heat, light, injury, and infection. It is the body’s largest organ. It is only about 2 millimeters thick and weighs approximately 6 pounds.
The skin is composed of two layers that cover a third fatty layer.
The epidermis is the outermost layer of the skin and is responsible for protecting the body from the environment. Its thickness varies on different parts of the body. For instance, it is only .05 millimeters thick on the eyelids and is 1.5 millimeters thick on the palms and the soles of the feet.
The epidermis is made up of five sublayers that work together to continually rebuild the skin’s surface.
The innermost layer of the epidermis is the basal layer. The cells in this layer continually divide, producing new cells that constantly push older ones up to the surface of the skin, where they are eventually shed. This layer also contains the cells that are responsible for our skin’s pigments, called melanin. Patches of melanin cause birthmarks, freckles, and age spots.
The squamous cell layer is above the basal layer and is the thickest layer of the epidermis. This layer contains the basal cells that have been pushed upward. These cells are now called squamous cells and produce the tough, protective protein that makes up the majority of the skin’s structure.
As the cells from the squamous layer are pushed up even further, through two more thin epidermal layers, they get bigger, flatter, and adhere together. Eventually they become dehydrated, die, and continue to migrate to the surface of the skin.
The outermost layer of the epidermis is called the stratum corneum. It is made up of 10 to 30 thin layers of continually shedding dead skin cells. This shedding process, where worn down cells are replaced by new layers of long-wearing ones slows down with age. Cell turnover takes 28 to 30 days to occur in young adults but requires 45 to 50 days in older individuals.
Located beneath the epidermis is the thickest of the three layers of the skin, the dermis. Much of the body’s water supply is stored here. It contains most of the skin’s specialized structures including, but not limited to:
* Blood vessels – to supply the epidermis with nutrient-saturated blood.
* Sebaceous glands – that secrete oil that helps keep the skin smooth and supple.
* Collagen – is the protein that holds the dermis together and is made by cells called fibroblasts. In the skin, collagen supports the epidermis, giving it its durability.
* Elastin – is a protein similar to collagen that allow the skin to snap back into place when stretched giving it its elasticity.
The subcutis, or hypodermis, is the innermost layer of the skin and consists of fat and collagen cells. Its thickness varies throughout the body and from person to person.
The above information should help you to assess anti-aging product ingredients and the aging skin issues they address.