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Varieties of wrinkles and the causes of their appearance

 
, medical expert
Last reviewed: 15.05.2018
 
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As you know, with any kind of aging, there is such a single sign, like wrinkled skin. That is why most methods of correcting age-related skin changes are directly or indirectly aimed at reducing the depth and severity of wrinkles. Moreover, many methods for assessing the effectiveness of various exposure techniques are based on assessing the state of the skin's relief (the method of skin "fingerprints"), counting the quantity and measuring the dimensions of wrinkles.

There are different types of wrinkles. They are distinguished by localization on the skin of the face and neck (for example, wrinkles in the forehead, eye angles, mouth circumference, etc.), in depth (superficial and deep), and also by the mechanism of formation (mimic or associated with a change in muscle tonus and gravitational ptosis of the facial soft tissues, ie, static ones). The chronological sequence of the formation of various wrinkles is well known. The first wrinkles, which can appear at the age of 20-25 years, are associated with a permanent contraction of face facial muscles. Over time, when the skin begins to suffer from chronological aging, there are both superficial and deeper wrinkles associated with the dehydration of the epidermis, the thinning of the dermis and the destruction of fibrous structures in it. Photographic aging, potentiating the effect of chronological aging, contributes to an even greater destruction of elastic fibers. The outcome of this process is the deepening of existing wrinkles and the appearance of a characteristic wrinkling of the skin, which is especially noticeable in the area of the skin of the cheeks. Later, with hormonal changes against the background of a sharp decrease in the density of the dermis, changes in the tone of the facial muscles and gravitational ptosis of the soft tissues of the face and neck, deformation of the face oval, skin of the eyelid, and other changes appear. This is accompanied by a deepening of the nasolabial folds, the appearance of deep folds from the corners of the mouth to the chin (the so-called "mouth of the puppet"), cervico-pancreatic folds and other wrinkles.

By now, information has been accumulated on the complex of morphological changes in the skin that occur when wrinkles are formed. Knowing the mechanisms of wrinkle formation is necessary for a professional to solve the problem of directed complex correction of this phenomenon.

Mimic wrinkles

More than 19 muscles provide mobility of the face when talking, chewing, opening and closing the eyes, smiling, frowning eyebrows, etc. However, only certain movements of the facial muscles lead to the appearance of facial wrinkles. This occurs only in those places where the muscles are located close to the superior dermis. Such areas include typical oblique lines in the projection of "crow's feet" on the skin in the temporal areas, horizontal lines on the forehead, vertical lines between the eyebrows and oblique lines in the circumference of the mouth. Until recently, it was believed that their occurrence was due solely to pulling up the dermis in areas of the most frequent contraction of facial muscles. Studies of recent years have shown that facial wrinkles are formed not only under the influence of contraction of the underlying muscles, but also as a result of spontaneous contraction of the dermal fibroblasts. It is known that the muscle cell is capable of contraction, due to the presence in it of a special submembrane complex - the system of tonofibrils and tonofilaments. The composition of tonofibrilles includes actin and myosin fibrils. When a nerve impulse is applied to the muscle cell, the calcium ions exit from the smooth endoplasmic reticulum (EPR), and thus trigger the biochemical reaction of actin with myosin. The formation of the actino-myosin complex is accompanied by a shortening of the muscle fiber due to the fact that the actin strands are "inserted" into the filaments of myosin and muscle contraction occurs. It has been shown that dermal fibroblasts are also capable of such a reduction due to the presence in them of a small amount of tonofilaments compared with myocytes. The impulse for their contraction is transmitted from the contracting striated muscles of the face. In the future, calcium is released into the EPR, under the influence of which the fibroblast fibroblasts are reduced. The reduced fibroblast tightens behind itself a complex network of fibrous structures of the dermis and epidermis, which is the result of constantly increasing degenerative-dystrophic changes in these areas of the skin. Thus, it becomes clear that the mimic wrinkle is formed due to a kind of constant "mechanical stress" in the dermis region. Not accidentally, some researchers identify a special kind of aging - myosthenia.

The formation of superficial wrinkles is associated with superficial changes in the skin - at the level of the epidermis and the upper parts of the dermis. Deep wrinkles are associated not only with superficial, but also with deeper changes - in the middle and lower thirds of the dermis. It is known that the normal pattern and texture of the skin surface is provided by a number of structures and physiological mechanisms. One such mechanism is the maintenance of a certain moisturizing of the stratum corneum. It is known that on the surface of the skin under physiological conditions a delicate balance is established between the water content in the stratum corneum and in the environment. Changes in the synthesis and the ratio of highly specialized lipids lead to a violation of the barrier properties of the skin and, consequently, transepidermal loss of water. Dehydration of the stratum corneum leads to the appearance of superficial wrinkles. Such a phenomenon can occur at a young age with the constant exposure to the skin of unfavorable environmental factors (low or high ambient air temperature to humidity, other climatic factors), irrational skin care (aggressive detergents, alcohol-containing solutions, inadequate moisturizing, etc.) , as well as some dermatoses (atopic dermatitis, ichthyosis, etc.). Changes occurring in the skin can be combined by a common term - "delipidization". Dehydration of the stratum corneum, along with thinning of the epidermis, is also characteristic of menopausal aging. The main triggering mechanism of these changes is the slowing down of the rate of proliferation of the basal keratinocytes of the epidermis under the influence of a decrease in the concentration of estradiol. Changes in the skin pattern, as well as superficial wrinkles, can be caused by uneven thickening of the stratum corneum. This phenomenon is typical for photoaging.

An important role in the appearance of wrinkles is played by the composition of the basic substance of connective tissue and the fibrous structures of the dermis. Certainly, the state of these structures depends largely on the functional activity of dermal fibroblasts. At the beginning of the last century, scientists noted that the initial signs of age-related skin changes are interrelated with the destruction of elastic fibers, and more delayed - both elastic and collagen. The oksitalanovye elastic fibers are most sensitive to various trigger factors of the environment, and they are the first to undergo destruction. A consequence of this are superficial wrinkles. When the elanin and mature (true) elastic fibers are destroyed, deeper wrinkles form. It is known that, after 30 years, elastic fibrous structures begin to undergo fragmentation and disintegration. In addition, with age, lipid deposition in the dermis activates the elastase enzyme and starts the process of elastolysis, that is, the destruction of the elastic fibers. Elastic fibers are most vulnerable to ultraviolet rays, so the described changes are especially characteristic for photoaging.

As for the tallagen fibers, they provide the framework of the stroma and their bundles are arranged in different directions. Recent studies in the field of aging skin biology have shown that after 40 years, not only the synthesis of collagen in dermal fibroblasts decreases, but also the production of these enzymes by special enzymes - collagenases, or matrix metallo proteinases (MMP). Collagenases like elastases, contribute to the destruction of fibers. The outcome of these processes is that the skin loses its elasticity and, as it were, "sags", and the wrinkles deepen. This process is most noticeable in the deforming type of aging, when there are deep wrinkles associated with changes in the tone of the facial muscles and gravitational ptosis of soft tissues. Thus, in any kind of aging, the fibers of the dermis are destroyed.

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