Epidermis - what is it? Structure of the epidermis

Skin, according to many dermatologists, is the most complex organ of man. The presence of a multitude of layers and various functions, an abundant network of blood vessels and entire groups of nerve receptors provide it the main place in protecting a person from environmental factors. Moreover, the skin also plays a communicative role, having the ability to receive tactile information from the outside world. And let the epidermis as the top layer is important only as a mechanical barrier, its value is very large.

General characteristics of the epidermis

The layer of dividing, maturing, dying and already dead cells is the epidermis. What it is? It is an entire tissue that has several layers, the cells of which come from the same source, but are located at different levels, depending on the degree of maturation. Epidermis is the first universal barrier, which is faced with any potentially dangerous for the body environmental factor.

Layered structure: layers of skin

The structure of the skin is layered - 3 layers, performing different functions. The most important of these is the dermal, with blood vessels, receptors and muscles. Also in the dermis are the hair. And their "ancestor", like nails, is the epidermis. What it is? It is a horny layer located directly above the dermis and playing a protective role not only in relation to it, but also the whole organism. Slightly deeper than the dermis is located a less important layer of the skin - cellulose, where fat accumulates in the adipocytes.

Layered structure of the epidermis

The deepest layer is the basal one, which is entirely represented by cells capable of division. Due to them, the damaged cells are restored and the lost horny scales are replaced. In the thickness of the basal layer there are individual melanocytes accumulating black pigment substance (melanin), necessary for ultraviolet protection of the skin.

The thorny layer is located above the basal layer and is constructed in the form of 3-8 rows of living cells already incapable of division. They are linked to each other through cytoplasmic outgrowths to give the skin a mechanical strength. In areas of skin exposed to frequent external influences, the number of layers of spiny cells increases to 8-10 pieces. In such places there are no sweat glands and hair: feet and palms. With frequent damage to other areas, the layers of the epidermis also thicken with the formation of calluses.

Immediately above the spiny layer is granular, which is represented by half dead epidermal cells. Their organelles lose their ability to generate energy, but they accumulate a significant amount of tonofibrils. The granular layer consists of only 1-2 cellular layers oriented parallel to the surface of the skin.

Brilliant is called a layer of cells completely devoid of organelles. Their purpose is mechanical protection of the skin and gradual withering away, degradation to the stratum corneum. The latter is superficial. This is a collection of dead scaly cells, which are an excellent barrier to pathogenic effects.

Functions of epidermal cells

The main function of the epidermis is the creation of mechanical, physical, biological and chemical barriers that delimit the internal environment of the body from potential and actually pathogenic factors. However, this is not all the roles that the epidermis plays. What is it, and how is this explained?

• First, the surface layer differentiates the body environment and the outside world to protect the body and to prevent the escape of important substances and components.
• Secondly, the epidermis protects against the ionizing corpuscular and wave radiation of low power, which the body meets day to day.
• Thirdly, the epidermis of the skin is a good chemical barrier, preventing the ingress and absorption of hydrophilic substances. And lipophilic (fat-soluble) is well absorbed by them.
• And the last in the list, but because no less important function - biological protection. There is a very small amount of bacteria and fungi that can infect a person through the skin. The main protective role in this case is the epidermis. What it is? This is a good mechanical barrier, which simply does not allow getting the virus, bacteria, fungus or parasite into the body, causing inflammation there.

Without melanocytes and keratinized cells, the functions of the epidermis would not have been realized. Epithelial cells play the role of a mechanical barrier, and melanocytes are an optical barrier. This means that the epidermis protects against damage and evaporation of the liquid, and the pigment cells - from the ultraviolet. All this allowed the person to adapt to the conditions that are observed in the familiar world. After all, it was the development of the skin that allowed the organisms from which man originated to get out of the water and subdue the land.

The main features of the epidermis

All layers of the skin were phylogenetically developed to provide certain functions. Epidermis is designed to protect the dermis from mechanical, physical and chemical influences. It is needed to limit the loss of fluid that can evaporate only from its surface after secretion by sweat glands. There is no other physiological way of leaking fluid from the body through the skin.

If we consider the epidermis from a cosmetic point of view, then the following facts are obvious. This layer of skin can not have wrinkles and scarring, it does not have blood vessels. It feeds on the diffusion of substances from the vessels of the dermis of the skin. Therefore, his only cosmetic problems are the following: hyperkeratosis (thickened layers of the epidermis) and skin peeling. The fight against these phenomena, as well as with psoriasis, requires the treatment and use of cosmetics.

Pathologies of the epidermis and melanocytes

There are several categories of diseases that the epidermis can suffer. What this is and how the data states are manifested, read below. The first category - diseases associated with increased reproduction of epidermal cells of the basal layer. The disease is called psoriasis. There is also a congenital condition ichthyosis, in which the infant is already born with hyperkeratosis and is not viable. The second group of epidermal diseases is tumor. From the epidermis can develop basal cell and melanoma. The latter originates from melanocytes.