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Skin Structure
Before we dive into spray tanning it is super important that you have a basic understanding of the skins structure. This knowledge will set the foundation of what is to come!
Your skin consists of 3 main zones:
- Epidermis– is the outermost layer containing the cells that produce pigment and protect the immune system
- Dermis– the next deeper layer contains sweat and oil glands, nerve endings and hair follicles
- Subcutaneous – this is the fat and connective tissue layers where you will also find the large blood vessels
We are going to focus on the epidermis layer
The epidermis is the most superficial layer of the skin and provides the first barrier of protection from the invasion of substances into the body.
The epidermis is the thinnest layer of skin, but it’s responsible for protecting you from the outside world, and it’s composed of five layers of its own:
| Name | Location | Function |
|---|---|---|
| Stratum basale (stratum germinativum)
(stray-tum bay-say-lee or stray-tum germ-in-a-tie-vum) |
Deepest layer of the epidermis. | New skin cells develop in this layer, and it also contains the keratinocyte (cur-at-in-o-site) stem cells, which produce the protein keratin. Keratin helps form hair, nails and your skin’s outer layer, which protect you from the harsh environment. It also contains melanocytes (mel-ann-o-sites), which are responsible for producing melanin, which provides the pigment of your epidermis. |
| Stratum spinosum
(stray-tum spin-o-sum) |
Between the stratum basale layer and the stratum granulosum layer. | This layer mostly consists of keratinocytes held together by sticky proteins called desmosomes (dez-mo-soam). The stratum spinosum helps make your skin flexible and strong. |
| Stratum granulosum
(stray-tum gran-yoo-lo-sum) |
Between the stratum spinosum layer and the stratum lucidum layer. | Keratinocytes have granules within them, and in this layer they’re visible under a microscope. |
| Stratum lucidum
(stray-tum loo-sid-um) |
Between the stratum granulosum and the stratum corneum. | The stratum lucidum is a thin, transparent layer of keratinocytes that are becoming less round and have a flatter shape.
This layer is only found on palms, soles |
| Stratum corneum
(stray-tum corn-ee-um) |
The top layer of the epidermis. | This is the layer of the epidermis that you see. In the stratum corneum, keratinocytes become corneocytes (corn-ee-o-site). Corneocytes are strong, dead keratinocytes, and they protect you from harm, including abrasions, light, heat and pathogens. This layer also consists of fats that keep water from easily entering or leaving your body. The corneocytes eventually shed as new keratinocyte cells develop in the stratum basale layer and move through the other layers of skin. |
What are the functions of the epidermis?
Each layer of your skin works together to keep your body safe, including your skeletal system, organs, muscles and tissues. The epidermis has many additional functions, including:
- Hydration. The outermost layer of the epidermis (stratum corneum) holds in water and keeps your skin hydrated and healthy.
- Producing new skin cells. New skin cells develop at the bottom layer of your epidermis (stratum basale) and travel up through the other layers as they get older. They reach the outermost layer of your epidermis after about a month, where the skin cells shed from your body as new cells develop at the bottom layer.
- Protection. The epidermis acts like armor to protect your body from harm, including ultraviolet (UV) radiation, pathogens (bacteria, viruses, fungi and parasites) and chemicals.
- Skin color. The epidermis has cells called melanocytes, which make melanin, which is a group of pigments in your skin that provides skin color.
How does the epidermis help with other organs?
In conjunction with your other layers of skin, the epidermis protects your skeletal system, organs, muscles and tissues from harm.
Cell Lifecycle
Complete cell turnover occurs every 28 to 30 days in young adults, while the same process takes 45 to 50 days in elderly adults until they die and join the stratum corneum.
Stratum Corneum
The stratum corneum is sloughed off continually as new cells take its place, but this shedding process slows down with age. This layer can be as deep as 30 layers.
This is the layer I want you to remember. All will be revealed shortly I promise!
