Skin is the most exposed part of the body in contact with external environment and with a very particular structure. It performs various functions, including the protective one against dangerous substances but no less important are the regenerative, metabolic, secretory, exchange, temperature regulation, sensory and reserve functions.

Skin structure consists of 3 fundamental layers:

EPIDERMIS: the outermost layer in which there are keratinocytes, cells becoming corneocytes, or flattened cells present in the outermost layer of the epidermis, the stratum corneum.

DERMA: middle layer containing blood vessels. Here are:

  • sweat glands that produce sweat and play a role in temperature regulation.
  • Hair follicles
  • Sebaceous glands: produce sebum which protects against dust and batteries.

 HYPODERMA: the innermost layer made up of connective tissue.

Each of us has a type of skin that changes based on some factors that intervene in its composition.


This type of skin hasn’t any kind of imperfections. It is, in fact, luminous, hydrated, homogeneous in the complexion and it is typical of young people.


Combination skin has to more sebum and oiliness in the so-called T-ZONE. It is not totally oily in all parts but has some imperfections such as pimples and blackheads. Combination skin is treated with astringent cosmetics containing Salicylic Acid and Niacinamide, purifying masks especially on the T-zone with Clay or Charcoal, light moisturizing and non-comedogenic creams.


This type of skin not only has an excessive secretion of sebum that makes it oily to the touch, but often has pimples, imperfections and in most serious cases acne in all face.

Excessive sebum production mainly depends on hormonal dysfunction.

Sebum lubricates skin making it more impermeable to moisture. It has an innate antibacterial activity and has an anti-inflammatory function.

The increase in sebum excretion, the dysregulation of the hormonal microenvironment, the proliferation of Propionibacterium acne and inflammatory processes are the main concomitant events associated with the development acne. If sebum interferes with the follicular keratinization process of the pilo-sebaceous gland, blockage clogged pores can occur, contributing to the formation of lesions and acne.

Oily skin should be treated with light oil-free products, clay masks, aqueous serums containing substances such as Retinol which acts on acne, Salicylic Acid which acts by preventing blockage of pores, adsorbent powders which regulate the production of sebum and probiotics for balancing the skin microbiota.


Dry skin has an imbalance of water and lipids in the stratum corneum, the barrier function can’t be performed effectively and the skin begins to manifest different degrees of disturbance such as dryness.

Dry skin is rough to the touch, more sensitive to external aggressions, it is often associated with itching, redness and in more serious cases such as xerosis, it shows cracks. The complexion is duller and more prone to wrinkles.

The condition of dry skin includes also dermatitis which is considered an inflammatory condition of the skin.

There’s a difference between dry skin and dehydrated skin: dry skin lacks water and lipids, dehydrated skin lacks water and there is a sensation of “tightening” skin.

Dry skin should be nourished with emollient creams rich in butters and oils. Excellent allies are Shea Butter and Almond Oil and if itching is present, it is necessary to resort to softening substances such as Panthenol, Mallow Extract, Calendula and Licorice.

Among the types of skin we must not forget mature skin and aging skin which have more or less marked roughness. In these cases there is a large thickness, the keratinocytes become shorter and fatter, while the corneocytes become larger due to the reduced epidermal turnover. Melanocytes decline at a rate of between 8% and 20% per decade, resulting in pigmentation in the skin. The production of sebum up to 60%.

This results in a loss of tone and the appearance of wrinkles. It is important to exfoliate the face with acids such as Glycolic and Mandelic, use Retinol in the evening to give brightness, Hyaluronic Acid to give tone and hydration and do not forget products with SPF to protect against the formation of dark spots.

Mara Alvaro

Dr. in Chemistry and techn. Pharmaceuticals

specialized in Cosmetic Sciences



1.    “Structure and functions of the skin”-Health and safety executive

2.     “An update on the role of the sebaceous gland in the pathogenesis of acne”-Evgenia Makrantonaki, Ruta Ganceviciene, Christos Zouboulis- Dermato Endocrinology

3.     “What do you know about dry skin”- Medical news today

4.     “Characteristics of the Aging Skin”- Miranda A. Farage, Kenneth W. Miller, Peter Elsner, and Howard I. Maibach-Advances in wound care

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