The Skin, also called Skin or Integumentary System, represents the largest organ of our organism, in fact it covers the entire body surface.
On average, it has a weight of about 5 kg and an area of about 2 square meters, while its thickness varies according to the body areas: 0.5 mm on the eyelids, 3 mm in the palm-plantar area, 4 mm at the nape, up to 6 mm on the heel in order to prevent lacerations that could occur while walking, thin at the level of the flexion folds, such as popliteal fossa or hollow of the elbow, thicker at the extensor surfaces of the limbs; it can undergo variations, producing more cells, if subjected to wear.
For these reasons, every part of our body requires a targeted and specific intervention system in order to keep the skin itself in an optimal state of well-being and functionality.
The skin is made up of 3 different tissues or layers:
- Epidermis or epithelial tissue
- Dermis or connective tissue
- Subcutaneous or hypodermis or adipose tissue
It is a layered epithelium called the lining epithelium; proceeding from
bottom to top is divided into 5 layers:
- Basal or germinative layer: cuboidal-shaped cells
- Spiny or filamentous or Malpighian layer: cells with a polyhedral shape
- Granular layer: flat and crushed cells
- Glossy layer
- Horny layer: flakes
At the basal level there is a continuous production of cells; they undergo a “push upwards”, up to the surface, to restore the now dried cells of the stratum corneum. In fact, during the ascent, the cells (keratinocytes) undergo variations and a crushing towards the top in a process called keratinization.
- The basal or germinative layer is made up of keratinocytes with an oval and extended nucleus and abundant cytoplasm; these cells, undergoing mitosis, are the only ones able to multiply, in order to allow the continuous renewal of the epithelium. Some of them remain in place, while the majority migrate to the upper layers, changing shape and content along the way. Under normal conditions, the number of cells produced in the germinative layer equals the number of cells eliminated in the stratum corneum.
Interposed to the basal cells, there are melanocytes, cells with a rounded shape equipped with a sort of extension, involved in the production of melanin. In fact, melanogenesis is the process that leads to the synthesis of melanin at the level of melanosomes, particular cytoplasmic organelles present in melanocytes. THE
granules of melanin, through the extensions of melanocytes, are released and absorbed by the keratinocytes, in order to define the skin and hair color and to protect against ultraviolet radiation.
- Above the basal layer, the keratinocytes take on an irregular polygonal shape, forming the spinous layer, so called because the cells are joined by thin cytoplasmic filaments, similar to spines or intercellular bridges, called desmosomes. Made up of 5-20 cell layers, it is the thickest of the epidermal layers.
- At the level of the granular layer, the keratinocytes acquire large cytoplasmic granules called keratoyalin granules, which are transformed into keratin following the keratinization process that starts in this layer and ends at the level of the horny layer. These cells are smaller in size, as the nucleus and cytoplasm are reduced, are flattened parallel to the surface, with a thicker cell membrane than the cells of the underlying layers and with less intercellular space; this leads to a reduction in nourishment leading to necrosis, drying and corneification, ie cell death.
- The shiny layer is detected at the palm-plantar level, sections in which the stratum corneum is very thickened, as it is more subject to wear. It consists of 1-2 strands of keratinocytes smaller than the previous ones, flattened, irregular and with dense cytoplasm containing a substance called eleidine.
- At the level of the stratum corneum, the keratinocytes complete the maturation process, transforming into corneum cytes, anucleated and therefore non-viable cells, with a flat and wide shape, devoid of cytoplasmic organelles. These cells are continuously lost from the skin surface in the form of scales or flakes.
To maintain the balance of the epidermis, between regeneration and loss, the cells produced at the level of the basal layer must be in equal quantities to those eliminated at the level of the stratum corneum.
The time taken by a cell in the basal layer to reach the stratum corneum is between 10-14 days; another 10-14 days are needed for a cell to cross the stratum corneum before being eliminated. Therefore, the turnover time in physiological conditions is 20-28 days.
Regularly practicing a scrub on face and body, favors the elimination of "dead cells" from the stratum corneum, helping to keep cell turnover balanced in order to guarantee brightness and silkiness to the skin.
The dermis is a tissue that performs 3 functions:
- Supports and nourishes epidermis and skin appendages
- Protects the skin by defending it from mechanical stress
- It's a water deposit
It consists of 3 components:
- Fibrous component
- Cellular component
- Fundamental substance
The fibrous component consists of:
a- reticular fibers
b- collagen fibers
c- elastic fibers
a- reticular fibers are the scarcer and form a reticulum
b- collagen fibers are the most abundant and are made up of fibrils, in turn made up of micro fibrils. Each collagen molecule is composed of 3 spiral-wound polypeptide chains: this gives the fibers rigidity and strength.
With age, collagen is qualitatively altered, since there are variations in physical properties and decreases in quantity; wrinkles occur as a result.
c- the elastic fibers are mixed with the collagen fibers and constitute a scaffolding for the dermis; equipped with a mechanical property, called reversible extensibility, they allow the skin to relax when pulled and to go back when released.
The cellular component consists of:
c- plasma cells
a- fibroblasts are elongated cells that intensively carry out protein synthesis and produce collagen, elastin and proteoglycans
b- histiocytes are cells that exert phagocytosis
c- plasma cells are involved in the synthesis of antibodies
The fundamental substance is a gelatinous portion that fills the spaces between the fibers and the cells; it's composed by:
The dermis is made up of 2 compartments: 1 - papillary dermis; 2 - deep or reticular dermis
1 - the papillary dermis is the most superficial and consists of:
- Thin bundles of collagen
- Numerous fibroblasts and capillaries
- Abundant fundamental substance
- Elastic fibers arranged perpendicular to the skin surface
2- the deep or reticular dermis extends to the subcutaneous and consists of:
- Large bundles of collagen arranged parallel to the skin surface
- Network of large elastic fibers
- Little fundamental substance
- Few fibroblasts and capillaries
It is the deepest area of the skin; it consists of adipose tissue divided into lobules by collagen fibers. In it, we find blood and lymphatic vessels, nerves, pilosebaceous follicles, sweat glands and furry muscles.
The adipose tissue is made up of adipose cells or adipocytes, roundish cells with a crushed nucleus and moved to the periphery, since the cytoplasm is filled with lipids.
The hypodermis plays the role of thermal insulator against excessive heat dispersion, performs a mechanical function of support and defense of the underlying tissues and constitutes a considerable reserve of energy.
- Thermoregulation, thanks to the cutaneous blood vessels and the eccrine sweat glands, keeps the body at a constant temperature (about 37 ° C)
- Protective barrier: protects internal organs by opposing the passage of microorganisms such as bacteria, fungi or viruses
- Protection from mechanical stimuli
- Sense of touch
- Protection from electric current
- Protection from external aggressions such as cold, heat, humidity, dry air and UV rays
- Relations with the external environment thanks to a dense nervous network
- Secretion of substances such as sebum and sweat and elimination of waste products
- Absorption of products and substances applied from the outside, a role mainly played by the stratum corneum.
The skin disperses water through an imperceptible evaporation towards the outside, the perspiratio insensibilis. Furthermore, a loss also occurs through the secretion of the sweat glands, loss influenced by factors such as altered stratum corneum, dry climate, etc.
Instead, the natural hydration of the skin is provided by the fatty acids present in the stratum corneum at the level of the intercellular spaces and the natural hydration factor or NMF, which consists of substances such as free amino acids, lactic acid, urea, which retain the water and, therefore, prevent its dispersion.
The stratum corneum deprived of NMF becomes rigid and fragile, so it is essential to ensure the hydration of your skin by applying creams and ointments with an emollient action. Moisturizing substances are defined as all those that penetrate through the skin barrier (they easily cross the barrier of fatty acids being liposoluble or lyophilic), prevent skin water dispersion, that is, they retain water and increase its content.
A greater moisturizing effect will be obtained if the skin surface is first moistened and then the moisturizing substances are applied; in this way, these substances will have more water to retain, due to their hygroscopic property. After a thorough cleansing, Alkemilla recommends the application of the tonic before applying the specific cream.
Anything that alters the stratum corneum leads to dehydration, or loss of the skin's water content.
Dehydration can in fact be the result of continuous mechanical trauma, that is the continuous rubbing of the skin, a too dry climate, the use of synthetic soaps, aggressive detergents, degreasing detergents, etc., which reduce both the thickness of the horny layer and the content in fats of the epidermis.
Alkemilla recommends organic detergents and shower gel with eudermic action.
Wrinkles are furrows that appear with age and beyond, in correspondence with skin lines.
We distinguish 2 types of aging:
- biological aging
- photoaging, also called photoaging
- Natural physiological aging, defined biological aging, can be accelerated by various factors: hormonal, liver disorders or to other organs, environmental factors such as excessive exposure to UV rays, environmental pollution, lifestyle, nutrition, exercise exercise, stress, hours of night sleep, smoking, use of synthetic products that weaken the defenses, etc. The phenomenon of skin aging can be more or less accelerated also on the basis of constitutional and genetic factors: in fact, individuals with the same age can present a different degree of aging; it is possible to verify differences also according to the body regions.
- The skin is a fabric in direct contact with the external environment, therefore it is exposed to wind, thermal variations, pollution and first of all, the sun. By photoaging, we mean skin aging due to continuous exposure to solar radiation.
The most affected areas of the body are those that are uncovered, i.e. the face and back of the hands.
The resulting effects are:
- Wrinkled, rough and atrophic skin
- Permanent dilations of small blood vessels (telangiectasias)
- Yellowish or brown or black pigmented spots
- In the worst cases, tumors
By combining the effects of biological aging and photo-aging, the so-called photo-induced premature aging results, whereby the subjects concerned will appear older in relation to biological age, since the resulting wrinkles are deeper than the physiological ones.
Furthermore, skin aging involves all structures of the skin and not just the superficial layer:
- The epidermis is a continuously renewing tissue (as many cells are born as are lost); with advancing age, this renewal is slower so fewer new cells are born and fewer cells tend to move away from the stratum corneum, tending instead to cement themselves and form a more compact layer.
Furthermore, with age, the availability of natural moisturizing factor and sebum also decreases: this leads to a reduction in the protective barrier and reduced hydration. For this reason, the skin appears dry and wrinkled.
Some individuals are affected by another phenomenon that generally occurs after the age of 50 or sometimes even after 30: on the back of the hands and on the face (most exposed areas), roundish and dark spots called age spots appear, which are caused by an accumulation of melanin in the basal layers of the epidermis as a result of repeated exposure to sunlight.
- At the level of the dermis, already after 30 years the activity of the fibroblasts is reduced and consequently the quantity of substances produced by them is reduced. In fact, fibroblasts synthesize collagen, which constitutes the scaffolding, the support of the skin (with age it changes in quantity and quality), elastin, a protein that makes the skin elastic and extensible within certain limits, which drastically decreases in adulthood. , proteoglycans, including hyaluronic acid, substances capable of retaining considerable quantities of water which, when swollen, form a sort of gel that gives firmness to the skin tissue. They are present in high quantities in childhood, but undergo a constant reduction starting from adolescence. Clearly, as this substance decreases, less water will be retained and therefore, the fabric will appear less stretched and supported.
- Hypodermis: the subcutaneous fatty tissue is reduced.
Skin aging also involves a slowing down of circulatory activity in the dermis, which obviously is reflected in the epidermis, consequently there is a lower supply of nutrients to the cells and a greater permanence of waste, which behave like toxins.
A further effect associated with it is the decrease in the immune defenses, in fact the decrease in the secretions of the sweat and sebaceous glands, together with the thinning of the skin, reduces the barrier function, making the body more sensitive to the attack of germs and penetration. of harmful substances.
In addition to the formation of wrinkles, with age there is also a certain fall towards the inside of the skin due to the relaxation of the muscles and therefore to the loss of muscle tone.
|DRY ECZEMA||FRAGILE||EXPANDED PORES|
|Most "gold" answers:
Insufficient surface hydrolipidic film, following a deficit in the activity of the sebaceous and sweat glands. Use cosmetic products that allow to rebuild the water reserve in the stratum corneum, opposing an excessive trans-epidermal loss and allow the hydrolipidic film to be reintegrated. Use mild detergents.
|Most "pink" answers:
Normal or sensitive skin, easily irritable or reactive when subjected to stress. To restore the physiological balance, Alkemilla recommends:
|Most "blue" answers:
Avoid too aggressive hygienic cleansing practices and use detergents that dissolve and remove the sebaceous film in a very mild way. Alkemilla recommends: