What is Dry Skin?
In common parlance, "dry" is defined as a skin lacking in skin lipids, with a thin and fragile appearance, which appears visibly inelastic, dehydrated and desquamated. Although not completely correct from the scientific point of view, the definition of dry skin is now accepted also in the medical-dermatological field, given that it gives a good idea of the peculiar characteristics of this skin disorder.
Features
At sight, dry skin is desquamated, thin, not very elastic and fragile; the dull and clear complexion gives it an unhealthy appearance. To the touch, dry skin is rough, arid, with an irregular texture. Often sensitive, dehydrated skin generally manifests premature aging phenomena: not surprisingly, in a dry skin many more wrinkles (even at a younger age) are observed compared to oily skin.
We have seen that the severity of the disorder varies from a minimum degree of skin dryness (slight desquamation) to severe xerosis of the skin with deep expression lines.
The degree of hydration (or dehydration) of the skin is assessed by means of the corneometer, an instrument able to estimate the water content of the epidermis based essentially on the analysis of the electrical properties of the skin. The evaporimeter is also a tool used to assess the degree of skin hydration: unlike the corneometer, the evaporimeter measures the loss of water through the skin.
Classification
In dry skin, the hydrolipid content of the stratum corneum is significantly lower than the physiological values. Referring to this definition, we can distinguish different types of dry skin, listed below:
- DRY SKIN DEHYDRATED (literally "water shortage"): the deficit affects the water component, which is important for the barrier function, for protection against irritants and for the mechanical properties of the skin. When it affects the face, the skin appears shiny, with large pores; often it has black spots.
- ALIPIDIAN DRY SKIN (literally "lipid deficient"): dry skin is due to insufficient sebaceous secretion. The lower production of skin fats makes the skin more fragile and sensitive, subject to wrinkles and other signs of aging. If it affects the face, the pores appear narrow and the blackheads are rare.
The situations described often coexist, giving rise to a more complex variant of cutaneous xerosis, known as ALIPIDIC DEHYDRATED DRY SKIN, in which the reduced secretion of sebum is associated with a lower functionality of the apocrine and sweat glands.
Please note
Dry skin should not be confused with asphyxiated skin, in which the increased sebaceous secretion obstructs the follicular lumen, causing an accumulation of sebum, cellular debris and bacteria inside it. As a result, the skin does not appear greasy, but tends to be dry and rough to the touch; similar situations are supported not only by excess sebum but also by hyperkeratosis (thickening of the superficial layer of the epidermis).
Causes
Research into the responsible causes of dry skin is not always so obvious and immediate. In fact, skin dehydration is subject to a series of climatic, constitutional, environmental, physiological and pathological factors that are not always easily identifiable.
Let's see, therefore, what are the causes most involved in the genesis of dry skin.
Environment and climate
It is now established that the amount of water present in the stratum corneum is heavily influenced by environmental humidity. In other words, when the external humidity decreases, the percentage of water in the superficial layers of the epidermis is also reduced.
After prolonged exposure to UV rays, cold, air conditioning, excessive heating or wind, the skin tends to dry out progressively. In such circumstances, it is important to interpret the alarm signals that the organism sends us: the skin - visibly stressed, dry and flaky - requires some small tricks that allow the skin to restore lost physiological barriers.
It is believed that a 10% skin dehydration is sufficient to drastically alter the ideal characteristics of the skin, namely plasticity and elasticity. Hence the importance of intervening as soon as the skin sends the first signs of suffering.
Genetic predisposition
Premature aging of epidermal cells can clearly depend on genetic and constitutional causes.
Age
As the age progresses, the skin inevitably encounters a series of physiological events that favor skin dehydration. In similar situations, dry skin is mainly related to the progressive thinning of the epidermis, the qualitative / quantitative alteration of the collagen connective fibers and the depletion of the hydro-lipid film.
deepening
The hydrolipidic skin film is a kind of film present on the surface of the skin, consisting of a hydrophilic component (NMF) and a fat-soluble fraction mainly given by sebum (95% of the total).
Diet
Nutrition plays a major role in the appearance of the skin. An adequate supply of water undoubtedly contributes to maintaining an elastic skin and in excellent condition. To moisturize the skin - thus avoiding dry skin - in addition to water it is good to guarantee the body a fair amount of unsaturated fatty acids, proteins and amino acids, which are very important to ensure the proper functioning of the dermis components.
Vitamin deficiencies
Also the lack of some vitamins (vitamin A in particular) can cause dry skin. It is therefore important to ensure an adequate vitamin supply to the organism also (and not only) to keep the skin healthy.
Aggressive cosmetic products
Prolonged use of aggressive, poor or alcoholic cosmetics can deplete the hydro-lipid film of the epidermis, thus promoting skin dryness. Even too frequent washing - especially when performed without the subsequent application of moisturizing and emollient products - can negatively affect the degree of skin hydration.
diseases
Some morbid conditions can alter the water content of the skin. Among the major defendants of dry skin we cannot forget diseases of dermatological interest such as psoriasis, allergies, ichthyosis and atopic eczema, and more complex metabolic pathologies, including hypothyroidism, Hashimoto's disease, renal failure, diabetes and liver cirrhosis.
drugs
Taking some pharmacological specialties can promote the appearance of dry skin. Long-term care with diuretics and hormonal contraceptives, for example, promote progressive skin dehydration.
