Skin Barrier - Function And Structure

Skin Barrier - Function And Structure

The skin is the body’s largest organ and it’s also the first line of defence to the outside world. It’s made up of three main layers: the hypodermis (deepest layer), the dermis (middle layer) and the epidermis (upper layer). The outermost layer of the epidermis is called the stratum corneum and it forms the ‘skin barrier’, a complex structure whose job is to keep moisture in and allergens and irritants out.1 The skin cells in the stratum corneum—known as corneocytes— are actually dead and they form only one part of the skin barrier.

The easiest way to picture the structure of the skin barrier is to think of a brick wall. The dead skin cells are like the bricks, providing strength and structure, and they’re held together with mortar—or, in the skin’s case, a mixture of lipids that fill the spaces between the cells and play an important role in water regulation.2 Proper water regulation is key to help maintain smooth, hydrated and healthy-looking skin.

While the skin can be extremely resilient, the skin barrier itself is sensitive to several factors like humidity, temperature, and pH, and requires the right conditions to function optimally.3,4

 

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References:

1. Matsui T, Amagai M. Dissecting the formation, structure and barrier function of the stratum corneum. Int Immunol 2015;27(6):269–80. 
2. Lindberg M, Forslind B. The skin as a barrier. In: Loden M, Maibach H, editors. Dry skin and moisturizers: chemistry and function. CRC Press; 2006. 
3. Engebretsen KA, Johansen JD, Kezic S, Linneberg A, Thyssen JP. The effect of environmental humidity and temperature on skin barrier function and dermatitis. J Eur Acad Dermatol Venereol 2016;30(2):223–49. 
4. Lambers H, Piessens S, Bloem A, Pronk H, Finkel P. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int J Cosmet Sci 2006;28(5):359–70.