The skin - the outer covering of whole body and its organism, which protects the body from a wide range of external influences involved in breathing, temperature regulation, exchange and many other processes. In addition, the skin is a massive field of different types of receptor surface sensitivity (pain, pressure, temperature, etc.).

Structure of the skin

The skin consists of epidermis, dermis and subcutaneous fat (hypoderm).

* The epidermis consists of five layers of epidermal cells. The bottom layer - basal - located on the basement membrane and represents 1 row of prismatic epithelium. Immediately above it lies a layer of ribbed (3-8 rows of cells with cytoplasmic outgrowths), followed by the granular layer (1-5 rows of flattened cells) and brilliant (2-4 a number of non-nuclear cells, the differences on the palms and feet) and the stratum corneum, which consists of multilayered keratinizing epithelium. The epidermis also contains melanin, which colors the skin and causes the effect of sunburn.

* The dermis, or skin itself is a connective tissue and consists of 2 layers - papillary layer, which are numerous growths that contain loops of capillaries and nerve endings, and the net layer containing the blood and lymph vessels, nerve endings, hair follicles, glands, as well as elastic, collagen and smooth muscle fibers that give skin strength and elasticity.

* Subcutaneous fat is composed of bundles of connective tissue and fat accumulation, permeated with blood vessels and nerve fibers. The physiological function of adipose tissue is the accumulation and storage of nutrients. In addition, it provides additional protection for thermoregulation and sexual organs.

Apart from the skin in the body has its anatomical derivatives - education, which are developed from the skin and its beginnings. Various selection glands located in the skin, are also part of the outer cover of the organism.

Derived elements of the skin

* Nails
* Hair;
* Scale;
* Skin cancer, which include:
o sebaceous glands that emit sebum, which serves as a lubricant for the hair and protects the skin;
o sweat glands, performing a selection from the body of water and dissolved products of metabolism. Evaporation of sweat is an important part of thermoregulation.
o breast (developed in women) produce breast milk, which is essential for feeding a newborn baby.

Human skin
The area of the skin of an adult reaches 1,5 - 2,3 m, 1 and the mass of the skin - 15% of the entire mass of people.

Functions of the skin

* Security protects the body from the action of mechanical and chemical factors, ultraviolet radiation, the penetration of microbes, the loss of water splashing outside
* Thermoregulatory due to radiation of heat and evaporation of sweat
* Participation in water-salt metabolism associated with sweating
* Excretory elimination of metabolic products with sweat, salts and drugs
* Deposit of blood in the vessels of the skin can be up to 1 litter of blood
* Endocrine and metabolic synthesis and accumulation of vitamin D, and hormones
* Receptor due to the presence of numerous nerve endings
* Immune capture, processing and transport of antigens and the subsequent development of immune response

Distinguish:

* Thick skin (palms and soles) - formed a thick (400-600 microns) epidermis, no hair and sebaceous glands;
* Thin skin (in other parts of the body) - consists of a thin (70-140 microns) of the epidermis, and there is hair and skin cancer. 1 Cocchi (from the Greek. Kókkos – “grain”) - Bacteria spherical shape. There are perfectly round and slightly elongated in the form of bacteria.

After cell division form depending on the stage of division structures, which are typical for certain types of cocci.

Distinguish:

* Streptococci: folded in the shape of the chain (eg enterococci, peptostreptokokki)
* Diplococci: stacked in pairs (eg, pneumococcus, Neisseria)
* Tetrakokki: put together 4 cells
* Sartsiny: put together 8 or more cells
* Staphylococci: a pile of stacked cells (eg micrococci, peptokokki)

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