Skin Deep

Boost your skin IQ: Terms to know

Knowing some of the science behind why your skin behaves, looks, and feels the way it does can help you to better understand how to care for your unique skin type. These are just a few of the important terms that you might come across when reading about your skin and which products might help or hurt it.


Everyone’s skin has a complex system of tiny organisms that inhabit it. This microscopic ecosystem is called the microbiome, which includes both the living organisms and their environment. For example, a dry skin type will have a different bacteria and fungi than an oily skin type. The bacteria in the oily environment is considered a microbiome as is the bacteria in the environment with less hydration.

Dr. Leslie Baumann.jpg
Dr. Leslie Baumann

The term “microbiota” refers to only the living organisms, not including their environment. Many microbiota are harmless or even beneficial to your skin. Others like P. acnes and S. aureus, can cause skin problems like acne and eczema. We are just beginning to learn which microbiota play a role in healthy skin and how the entire microbiome plays a role in this.

For example, the microbiota such as P. acnes bacteria that causes acne may not cause a problem in dry skin that does not have a lot of oil on it. However, in the microbiome setting of P. acnes with excessively oily skin, acne is likely to occur.


In a previous Miami Herald column, I explained new research that shows how taking certain oral probiotics may help to alleviate eczema symptoms. Probiotics are living organisms that are administered orally or topically to achieve a specific health benefit. In this case, the oral probiotics would benefit the skin by preventing inflammation associated with atopic dermatitis, or eczema.

Not all microorganisms act as a probiotic in all environments. We are still researching which probiotics might help to treat various skin conditions, including acne, eczema, and rosacea.


The epidermis is the outermost layer of your skin. Within this layer, there are five sublayers: stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and the stratum corneum.

The stratum corneum is the top layer of the epidermis. This is the layer of skin that you can see and touch on the surface of your skin. Since it is exposed to the atmosphere, the stratum corneum is also the layer of skin that provides a protective barrier. In healthy skin, this layer prevents water from evaporating into the atmosphere, while also keeping out harmful germs, pollutants, and other particles. When the stratum corneum is impaired, dry, flaky skin cells can build up on the surface of your skin and result in a number of skin conditions.

The stratum granulosum is the layer that important skin elements are made, such as structural proteins and hydrating lipids (fats). These are made inside granules in this skin cell layer and are then ejected outside of the cells into the space between cells where they play important roles. The stratum spinosum derives its name from the fact that the cells are held together by little spines that make the skin stronger. Different skin diseases can affect various layers of the epidermis.

Desquamation vs exfoliation

The terms “desquamation” and “exfoliation” are often used interchangeably. Although they are very similar, there is one key difference. Desquamation is the naturally occurring process in which the stratum corneum layer of your skin sheds old flaky skin cells and replaces them with new fresh ones. Those cells travel all the way up from the deepest basale layer to the stratum corneum.

Exfoliation is an external process that we sometimes use to speed up natural desquamation. To achieve this, we can use chemical exfoliants, such as hydroxy acids or retinoids, or physical exfoliants like abrasive facial scrubs or microdermabrasion.

Dermatologists spend 12 years in school learning about all of these cell layers and how they are affected by nutrition, medication, skincare products, the microbiome, chemicals, light, genetics, and disease. The skin is the largest organ and is very complex.

This month on social media, I am concentrating on teaching you a bit of the science that dermatologists consider when helping you achieve your healthiest skin. Follow me @Baumanncosmetic on Facebook or Instagram if you are interested in brushing up your skin science skills and vocabulary.

For more information and videos on skin science, follow Baumann Cosmetic on YouTube, or follow @BaumannCosmetic on Instagram or Facebook.