Leather

The skin is the outer covering of the body is the body of the extremely complex structure that performs a number of important life functions. In addition to protect the body from harmful external influences, leather performs receptor, secretory, the exchange functions, plays a significant role in thermoregulation and other
The area of the skin of the adult person reaches in average 1.6 m2. Skin color depends on the transmission of blood and more or less the presence of melanin pigment. In the field of natural holes (mouth, nose, anus, urethra, vagina) leather enters the mucous membrane. On the skin surface can be detected peculiar pattern of triangular and rhombic fields limited grooves; it is especially distinct on the palms, fingers and soles. Almost throughout leather covered with hair.

the structure of the human skin
Fig. Throne skin of a human finger: 1 - 5 - epidermis (1 - basal layer; 2 - thorn layer; 3 - granular layer; 4 - shiny layer; 5 - the Horny layer); 6 - excretory duct of the sweat glands; 7 and 8 - dermis (7 - papillary layer; 8 - reticular layer); 9 - end Department sweat glands; 10 - fatty tissue.

The structure of the skin. In the skin, there are two sections: the upper - epithelial (epidermis) and the lower is the connective tissue (actually a skin - dermis). The border between the epidermis and dermis is represented in the form of rough wavy lines due to the presence on the surface of the dermis special processes, the so-called dermal papilla (Fig. 1).
The epidermis is composed of five layers of cells. The epidermis layer, located directly on the border with dermis, is called the primary basal layer. It consists of the same number of cells separated narrow slit tubules and interconnected protoplasmatic processes. The basal layer cells characteristic of two features: 1) they constantly reproduce and by differentiation make cells overlying layers; 2) in these cells formed and contains a pigment called melanin.
The second layer is called subulate. It consists of several rows of irregular shape of the cells with a bright core, also separated by slit tubules. The third layer is called grainy: it consists of one or two rows of long, elongated cells, closely adjacent to each other.
8 the cytoplasm of them are grains of keratohyalin, which is the first stage of education Horny substance. The fourth layer is called brilliant. It is found only on sites with a thick skin on palms, soles), is a shiny strips, consisting of flattened non-nuclear cells, and is the next stage in education Horny substance. The last, the top layer of the epithelium is the outer layer consisting of thin non-nuclear cells, are closely interconnected and containing a special protein - keratin. In the outer part of the stratum corneum less compact, a separate plate behind each other causing permanent physiological discharge of dead epithelial cells. The thickness of epidermis and, in particular, its stratum corneum on different parts of the skin varies. The most powerful it on the palms and soles, much thinner on the lateral surfaces of the body, especially thin on the eyelids and external genitalia of males.
The dermis is the connective tissue of the skin consists of two layers: podpisannogo, the so-called papillary and reticular. The papillary layer built from ninoaaeei connective tissueconsisting of thin beams of collagen, elastin and argyrophilic (reticulin) fibers. Last on the border with epithelium with interstitial substance form the so-called the basal membrane, playing a major role in the exchange processes between the epidermis and the dermis. Collagen fibers papillary layer gradually become more thick beams mesh layer and forms a dense tangle with a large number of elastic fibers. In the mesh and the papillary layer contains various cellular elements (fibroblasts, histiocytes, the fat cells and other); among connective tissue fibres laid small bundles of smooth muscle related to hair follicles.
Thick bundles of collagen fibers mesh layer is transferred directly into the subcutaneous fatty tissue, where they form a wide network loops which are filled with fat cells. Fatty tissue causes a flexible attachment of the skin to be fabrics and protects it from mechanical damage and breaks.
The skin has a large number of blood and lymphatic vessels.
Blood vessels form the two networks. The first of them is located on the border between the dermis and subcutaneous tissue, depart from it smaller vessels in the reticular layer of derma. On the border with papillary layer they fan out and form a second network which goes capillaries penetrating papillae (capillary loops). Venous vessels form the three networks. One of them is located under papillae, the second - in the bottom half of the dermis and the third - in subcutaneous adipose tissue. The epidermis is deprived of blood vessels and fed by the dermis. Lymph vessels form in the dermis two networks: superficial and deep.
The nervous system of the skin consists of numerous running through the nerve fibers in the dermis and special limit formations, the so-called encapsulated cells (bullock Meissner, Vater, Pacini, Ruffini, Krause's bulbs). Innervation of the epidermis is thin nerve fibrils, penetrating on intercellular channels primary and thorn layers.
The skin appendages include hair (see), nails (see), the sweat glands (see) and sebaceous glands (see).