The epidermis is the surface layer of your skin that you can see. It has between fifteen and forty layers of dead skin cells, depending upon its location. These cells are produced at the very bottom of the epidermis, where they slowly move upward towards the surface. As they ascend, they produce keratin and keratinocytes that both interact together to kill the new cells (called keratinization), making them very hard, exceptionally resilient, and a perfect protective barrier between your internal organs and the external environment. Once they reach the surface, these dead cells cause existing surface cells to be shed and replaced by the incoming cells. This replacement of cells from the bottom of the epidermis to the surface is called the cell renewal process, and it can take between four to six weeks in young adults. Finally, you can find a substance called melanin in this layer. Melanin gives your skin its color. The darker you are, the more melanin you have in your skin. The epidermis is where Refreshen microdermabrasion performs its magic, giving the user anti aging effects.
The dermis is the layer of skin that lies underneath the epidermis, and it is composed entirely of living cells. The dermis contains blood vessels, collagen, elastin, sebaceous glands, sweat glands, and nerve endings. Blood vessels are responsible for keeping your skin cells healthy by delivering oxygen and essential nutrients and removing waste. Collagen and elastin fibers both provide your skin with its inner strength, firmness, and elasticity. Sebaceous glands produce sebum (oil) that lubricates and protects your skin. Your sweat glands produce small amounts of sweat that work in tandem with sebum to form a protective layer that keeps the skin from absorbing water and getting soggy. Finally, nerve endings within the dermis allow your skin to sense touch, pressure, pain, and temperature.
The last layer of your skin is called the hypodermis, but often referred to more commonly as the subcutaneous layer. It contains adipose cells (fat) that act as a cushion for the skin, helps your body stay warm, and absorbs shock. The hypodermis also is responsible for anchoring your skin to all the tissues underneath it. Hair follicles are also located here and contain one or more additional sebaceous glands to help condition the hair and skin.