What first comes to mind when we think of organs are usually the internal organs of the body. What most of us don't realize is that we are covered by the largest organ of the body. Our skin. To understand the benefits of skin care it's important to understand the largest organ of the body. What makes the skin so unique is that it is a means of communication with the external environment, and it is barrier of protection against the external environment. The skin goes through continuous maintenance through a life cycle as a process of renewing itself. This process has phases. Before we go any further into the skin's life cycle, let's first understand the anatomy of the skin.
The Skin Divided Into 2 Layers
Epidermis - the outermost layer of the skin.
Dermis - the layer underneath the epidermis
The epidermis is the outmost layer of the skin that provides first line of defense against harmful external factors. It contains 5 sub-layers.
- Stratum Corneum - top, thick layer and comprised of about 20 to 30 layers of dead skin cells
- Stratum Lucidum - thin, translucent layer of dead skin cells present only in areas of the body that have think skin such as the palm of the hands and the soles of the feet
- Stratum Granulosum - thin layer of cells that contain keratinocytes that migrate to this layer and become granulocytes
- Stratum Spinosum - thick, spinous layer of skin cells that contain keratinocytes
- Stratum Basale (Germinativum) - the deepest layer of the epidermis, only one-cell thick, and made up of basal keratinocytes which are the stem cells of the epidermis; melanocytes (melanin-producing cells are responsible for skin color) are located in the basal layer
The dermis is made of irregular, dense connective tissue. It serves as a means of communication through nerve endings that provide the body with information through the sense of touch, allowing to feel pressure, heat, cold, pain, and texture. The dermis also houses the hair follicles, sweat glands, oil glands, and blood vessels. Blood vessels allow the blood to carry oxygen and nutrients to the skin and to carry away waste.
The Life Cycle of the Skin
The skin completes a life cycle in approximately 50 days. Cells from the bottom layer of the epidermis are pushed up toward the outer layer of the skin as newer ones are made. The dead skin cells at the surface eventually slough off making way for the new ones underneath to die and become the skin's new protective barrier. The average life-span of the skin cells before dying and reaching the stratum corneum is about 2 to 3 weeks.