Is the outside of the skin really dead?
Technically, yes, at least for the outermost layer of the skin. The outermost layer of the skin is the epidermis and is the first line of defense against dehydration, bacterial invasion, and irritant penetration. This is the layer that is addressed when we are using a skincare program. The cells in the epidermis go through many biochemical changes, and there many functions of this layer even though most of it is technically dead. There are three types of active cells in the epidermis which include basal cells, melanocytes, and Langerhans cells. Melanocytes are pigment producing cells that are found in both the lower epidermis and the dermis. Melanocytes give skin its color and are responsible for tanning. The Langerhans cells are immune function cells that patrol the epidermis to detect foreign invaders and pathogens. The basal cells are the cells that make new skin cells in the epidermis.
How does the skin renew itself?
The cells in the outer layer of the skin, the epidermis, begin as live cells in the lowest layer of the epidermis known as the basal layer. The basal cells divide in a biological process called mitotic division forming new cells. The cells are pushed upward. As they approach the surface the cells go through a process called keratinization. During this process the cell are filled with a protein called keratin. Keratin’s main structure in the skin is to make the skin surface more resilient and resistant to invasion of foreign substances such as bacteria. It also helps to keep the skin from becoming dry and dehydrated.
Is any part of the skin alive?
Yes! We have just discussed the epidermis, containing mostly dead and dying cells. However, we have also learned how active this layer is biologically. The skin is actually the largest organ in the body. The dermis is the layer under the epidermis and is very much alive. The live layer contains blood and blood vessels and the epidermis does not. The epidermis sheds and renews itself constantly. The dermis does not shed or have a renewal cycle, but does contain blood vessels that nourish many active and different living cells in this area.