Dry skin and moisturizer

Department Name : Dermatology / Professor Name: Won Young-ho

"Dry skin" is simply misunderstood as the opposite of "oily skin" from a cosmetic point of view, and mistakenly thinks that it is caused by a lack of fat in the skin. But not necessarily. For example, the sebaceous secretion of the sebaceous glands becomes active only after puberty. In practice, however, skin secretion is small in children, but the skin is more elastic than adults and the skin is very rarely dry. The stratum corneum of the skin must always maintain 10-30% moisture to perform its normal function. The high fat content and the water content are separate issues.
Dry skin is not just a cosmetic problem, it is not a simple skin disease. It is a type of reaction that appears as a symptom in various unrelated diseases. For example, it is caused by hereditary diseases such as young gland, winter xerosis, chronic irritation and allergic contact dermatitis, eczematous diseases such as atopy, sun damaged skin, etc. The first objective phenomenon of dry skin is scale. Skin epithelial cells migrate and grow from bottom to top, eventually becoming keratinocytes in the outermost layer (see figure). These keratinocytes, or keratin, are continuously and gradually desquamated without our awareness. However, in a pathological situation, thousands of keratinocytes are eliminated at once, which is called scale. When this occurs, the skin surface becomes whiter to the naked eye, and the skin feels rough, tattered, and dry.
Dry skin almost always causes itching. Itching is of great medical importance. In severe cases, it interferes with sleep, reduces concentration, lowers the quality of life, and makes people depressed. When scratched, itself physically damages the skin barrier. Due to this, bacteria existing on the skin may penetrate directly into the skin and cause infection. In this case, even if it causes an infection, there is no fever, and there are many cases where there is no festering phenomenon in a specific area, so the overall body condition is poor, and you feel tired and drowsy. Such cases are particularly common in elderly patients. And "scratching" the skin is an instinct to temporarily relieve itching by giving a stronger stimulus. However, debris from the stratum corneum enters the dermis, causing more inflammation in the skin, and thus shows a vicious cycle of feeling more severe itching.
In special cases, that is, in a patient who is unable to move the body due to chronic disease or damage to nerves or bones, the skin in a certain area is constantly compressed to prevent a smooth blood supply, resulting in skin ulcers. In this case, "dry skin" precedes the site as a precursor symptom, and by protecting the skin with a moisturizer in advance, the formation of ulcers can be prevented. On the other hand, skin aging is promoted on the back of the hand or face exposed to sunlight, and the elderly often suffer from purpura in which red blood cells are leaked from blood vessels due to minor damage. In this case, since red blood cells are leaked into the skin, bruises persist for a long time and often leave white scars, and purpura caused by damage can be reduced by appropriately using a moisturizer.
Moisturizers are used to improve dry skin. The moisturizer is called "Moisturizer" because it comes from moist in English. However, the term itself is a “new word” arbitrarily used in the United States to convey the meaning of moistening, softening, and supple skin for the promotion of a product. However, literally taking a shower several times a day to moisten the skin, or frequently immersing dry arms or legs in water does not make the skin moist, but rather, it results in harmful effects on the skin, and the skin becomes very dry. . The reason is that substances that are naturally present in the skin itself, so-called "natural mosturizing agents", are removed.
For convenience, moisturizers can be defined as substances used to soften and soften rough skin by reducing the symptoms and symptoms of dry and scaled skin. There are countless ingredients used in moisturizers. The most commonly used is to synthesize and use "natural moisturizing factors" that are naturally present in the skin. These are mainly low-molecular substances that absorb water and are composed of lactic acid, pyrollidone carboxylic acid, and amino acids. Moisturizers are largely classified into two groups depending on their action. The former are humectants, and are also included as the main component of NMF. ), etc. belong here. However, when applied to the outside, if the humidity in the surrounding environment is high, there is no problem, but when the humidity in the surrounding environment is low, the humidity is absorbed by the skin itself, so it is not used alone. Emollients are fats that do not mix well with water, such as lanolin, petrolatum, and various vegetable oils. In theory, when applied to the skin, it forms a film on the skin surface so that water does not radiate from the skin to the outside, thereby maintaining humidity. However, depending on the type, some things are absorbed directly into the skin, or they are mixed with water to change into an emulsifier.
Moisturizers are various combinations of ingredients with various moisturizing factors and other pharmacological functions. It not only improves dry skin, but also helps to treat skin diseases such as atopic dermatitis and psoriasis, or to improve aging skin. There is also a cosmetic effect of smoothing the skin by removing dead skin cells that roughen the surface. However, sometimes itching, burning, and stinging neurological symptoms, especially on the face, may occur. Many general people tend to prefer natural products due to the effect of encountering too many damages of various pollution and synthetic toxic compounds through newspapers and broadcasts in recent years. have. However, since it is a natural product, there is no scientific evidence that it is safe and effective, and sometimes it is rather harmful.

Common pathological symptoms in various diseases or situations that cause skin dryness are abnormal keratinocyte dropout and itching, but the abnormal stratum corneum is caused by abnormal epithelial cells below it. Therefore, treatment should also more fundamentally correct the abnormality of the epithelium rather than simply solve the problem of the stratum corneum, and selecting an appropriate moisturizer according to an accurate diagnosis is one method.

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