Building, composition and hair growth
Hair is horny filamentary formations, skin appendages that form hair cover and cover 95% of human skin (with the exception of palms, soles, rear surfaces of the fingers, red brown bits and some other areas). Hair protect the body of a person from heat loss and mechanical damage.
There are three types of human hair – long, bristy and powder.
Long hair is characterized by a dense, long long and fast growth compared to flush and bristle. They are thin and soft. These include the hair of the scalp, axillary depression, genital organs, mustache and beards in men.
Bristly hair – short, thick, relatively solid and have a color (pigmented). These include hair eyebrows, eyelashes, nostrils and external parts of hearing aisters.
Puffed hair do not have cores (brain layer). They are usually short (about 1.5 mm long), soft, colorless, covering almost all of human skin, with the exception of parts mentioned above (palms, feet and t.D.).
Structure of hair
Man’s hair consists of two parts; Rod (trunk) and root.
The rod is the visible part of the hair that protrudes over the skin surface. The root of the hair is in the thicker of the skin (dermis) and lies in it at different depths.
The extreme part of the root is a bulb, with a hairpin adjacent to it, which is permeated with blood vessels and nerves. It is through a papilla that hair is carried out. If the papilla is dying, then dies and hair. But if the hair dies (for example, breaks down with the root), and the papilla is preserved, then a new hair grows in this place. Volos growth occurs due to the breeding of bulb cells.
The root of the hair is enclosed in the hair bag called the follicle.
Song glands are attached to each follicle (they are usually 2-3), sweat glands and hair muscles that raise hair. Under the action of cold or emotions (fear, stress), the muscles are strained and how they like their hair on the head (in this case, they say that the hair has become end).
Sing glands highlight skin fat, or the so-called secret of the sebaceous glands. The main function of the hydro gland is the lubricant of the hair with sebum and formation on the surface of the skin with an emulsion film that performs a protective function: prevent the reproduction of microorganisms on the surface of the skin, skin opening, prevents excessive drying. Another important function of the emulsion film is to protect the skin and hair from ultraviolet rays. In general, skin fat gives hair shine and beauty, softens the hair, preventing from drying.
The total number of sebaceous glands in a person is about 200 thousand, and the total amount of skin fat produced by them reaches 50 g per day. The activity of the sebaceous glands depends on the floor, age, the state of nervous and endocrine systems, as well as from the structure of the power structure. If the skin saline is distinguished too much, it leads to the formation of a fat dandruff.
The structure of the rod of Volos
Three layers are distinguished in the hair rod: outer (cuticle), medium (cortical) and internal (brain).
The structure of the hair rod:
1. outer layer (cuticle);
2. cortical layer;
Outdoor (outer) layer of hair, i.e. cuticle, consists of rectangular scaly plates (oroging cells), located tiles, closely interconnected by the skin. The strength of the hair depends on this layer.
The medium, cortical, layer of the hair is its main mass and consists of spindle-shaped horny cells containing melanin (coloring pigment, from which the color of the hair is depends), and air bubbles. The thicker this layer, the stronger and more elastic hair.
The third – brain-layer of the hair (its core) consists of cells having a flattened round shape that has not yet been buried (keratinized). This layer affects hair shine and their shade through large intercellular and intracellular spaces. Magazin layer is absent in the powder hair and at the ends of the long hair of the head.
Hair consists of two main substances – keratin and pigment.
Keratin – a durable elastic protein characterized by a high content of sulfur (4-5%) and nitrogen (13.92%), which constitutes the basis of the horn layer of the skin, hair, nails and contributing to the energies of cells. Distinguish soft and solid keratin. Hair refers to structures containing solid keratin, but some hair components produce soft keratin.
Pigment is melanin. In the hair it happens in two forms – diffuse and in the form of small grains of various sizes. These molds of melanin give various combinations in the hair: in red hair a lot of diffuse melanin and little in the grains, in the ash hair a lot in the grains, little diffuse. From the color and amount of diffuse melanin, as well as the combination of grain and diffuse melanin, mostly depend on the color and shades of the hair.
By itself, the coloring pigment is three colors: red, yellow and black. Various color shades (their number reaches several tens) obtained by combining the main colors.
The main colors of the hair are black, brown, redhead, blonde, ash. In turn, brown is divided into blond (light brown) and scattered (dark blonde or chestnut).
Over time, the coloring pigment is replaced by air bubbles, so the hair begins to lose their color, that is, sew.
Hair growth is one of the indicators of their health. Various factors affect hair growth. In the afternoon, the hair grows slightly rather than at night, in the spring and in summer rather than in the fall and winter.
Hair pass several growth cycles. The first cycle is an active growth, then the rest stage goes.
During the period of active growth, the cells in the root of the hair are divided very quickly, which is why the hair grows. It used to be believed that new hair cells are formed in the hair onion, and now scientists have found that in fact the cells are formed in the thickening of the hair, which is located next to the skin surface.
Grow hair at speeds about 0.35-0.40 mm per day. The length of the hair increases in 1 month by an average of 1-1.5 cm. Fresh beard hair grow faster, very slow eyebrows.
With an increase in the age of a person, hair growth becomes less; The least age in this regard is reflected on the hair of eyebrows. The lifetime of one hair can last from several months to several years, depending on the care of hair, health and the state of the hairproof. The duration of the hair’s stay in the skin is limited and exposed to significant fluctuations not only from various people, but also at the same person at different times of his life. It is believed that the hair of the head holds 2-4 years, the hair of the eyelashes – 3-4 months, after which they are replaced by new.
About 25 full hair growth cycles have been programmed genetically during the human life.
Before losing the hair, the reproduction of bulb cells stops. Cells are protected and climbed together with old hair up (to the mouth of the follicle). As a result of this hair process drops. The growth of the new hair begins with the regeneration of the bulbs and directly depends on the good nutrition of the papilla, and the normal functioning of the papilla depends on the way it is supplied with blood.
On the scalp is a branched network of blood vessels. That is why the skin of the head is experiencing a stronger blood need compared to other parts of the body. Stimulate papillas, and sometimes to return them to life can be influenced by massage.
With every hair change, the hairpin is a bit raised upwards, in connection with which new hair is sitting less deep. Over the years, the cycle of the hair development is shortened, they change their structure (become land and thinner).
Many pregnant women notice the rapid growth of hair on the head – this is explained by the fact that during pregnancy there is a hormonal restructuring. The elevated level of female hormones affects hair growth, but after pregnancy, the hair begins to fall out and eventually become the same as before.
Correct direction of hair growth
The direction of hair growth is considered correct when the hair of the dark zone is growing in the direction from the crown to the forehead, the hair of the temporo-side zones – from the top and the pattern down to the ear shell, and the hair of the occipital zone – down to the edge hair growth line on the neck.
Different people have a hair rod can be located at a different angle to the skin surface – from 10 to 90 °. With too small angle of growth (10-20 °), the hair is very poorly stacked in the opposite of their natural direction. It is very difficult to make the desired hairstyle.