Skin is the largest organ of the body. It defends our bodies from external aggressors, maintains body temperature, excretes waste matter, gives sensory information to the brain and regulates body moisture.
Skin is a physical barrier to the environment. It is the alteration of the barrier properties and actual damage to this barrier that causes dryness and dermatitis when our skin is exposed to soaps, gloves, chemicals, water and harsh weather conditions. The repair of the damage by moisturizers is related to the physical and chemical interactions of the ingredients with the natural skin barrier.
Finding an adequate sensitive skin care solution requires the understanding of some basic facts about your skin.
Skin Physiology: Structure and Function Basics
Skin has two main structural layersthe epidermis and the dermis.
- The epidermis is the outer layer of skin, which serves as the barrier that impedes external environment from affecting the interior of our organism, physically or chemically.
- The structural support of the skin depends on the deepest layer of the skin, called the dermis.
Epidermis and Stratum Corneum: The Structure and Growth of Skin
The epidermis consists of stacked layers of cells in transition. These cells are connected by protein bridges called desmosomes.
- The bottom layer of cells adjacent to the dermis are the basal cells which reproduce; they are in charge of skin cellular regeneration
- As the cells mature, they move towards the outer layer of skin leading to terminal differentiation of the cells. During the process of maturation, the physiology, chemical composition, shape and orientation of the cells change.
- At the final stage, cells are called corneocytes, and they are already dead when they reach the stratum corneum, the top layer of the skin. Corneocytes lack a nucleus and cellular structures.
- Corneocytes are flat, hexagonal-shaped cells filled with water-retaining keratin proteins surrounded by a protein envelope and lipids. The stratum corneum gains added strength thanks to the shape and orientation of these cells. There are 10-30 layers of stacked corneocytes.
- There are more layers of stacked corneocytes in the thicker skin on the palms and soles.
- Protein bridges called desmosomes keep the cells connected to each other. Stacked bilayers of lipids surround the cells in the extracellular space. The resulting structure is the natural physical and water-retaining barrier of the skin.
Filaggrin: The Breakdown of Skin
During the process of maturation, the viable cells moving towards the stratum corneum start to clump proteins into granules.
- These granules are present in the granular cell layer of the skin and are filled with a protein called filaggrin.
- Filaggrin becomes complexed with keratin proteins in the granular cells. This way, proteolytic breakdown won't affect filaggrin.
- The keratin-filaggrin complex will be enzimatically broken as the degenerating cells move towards the outer layer of the skin; this break down discard devitalized cells and rejuvenate the skin
- In the stratum corneum, water-retaining keratin remains inside the corneocytes, while filaggrin stays outside them.
When the moisture content of the skin is decreased, specific proteolytic enzymes in the stratum corneum are triggered to further disintegrate filaggrin into free amino acids. At this stage, a revitalizer serum will be useful to aid skin restore itself.
A safer and natural option to chemical skin care solutions is now available in the shape of a skin care product to treat a wide range of skin conditions.
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