Hair - is it simple or difficult? Simple - only at first glance, but in reality - rather difficult, and even very difficult. For example, it's no secret to anyone that hair lives and dies - it grows and then falls out. And in their place (normally, of course) the same new hair grows.

What is the real purpose of a potential "mini-factory" for the production of hair (that is, a hair follicle in which phases alternate cyclically - first there is an enhanced synthesis of cells, and then this process is inhibited and completely stops)? Why did nature come up with such a highly organized energy-consuming system? Unfortunately, today scientists cannot give an unambiguous answer to these questions, although there are already several hypotheses. Maybe soon it will be possible to get answers, since most of the latter theoretical works in the field of dermatology and trichology are devoted specifically to the study biological clock hair follicle and cell differentiation processes.

Today Scientific research reached such a height that it became possible decryption genes "responsible" for hair loss; there are developments concerning the "reprogramming" of the genetic information responsible for the amount of hair on the head, etc.

But in order to understand all this, you need to start with minimal knowledge about the structure, composition and phases of hair growth.

How hair works. Human hair structure

You've probably heard before that hair is a dead substance. Is it so? And so and not so! From the point of view of physiology, the hair shaft that we see is a substance that cannot rightly be called living. It is not supplied with blood, nerve fibers do not fit to it and muscles do not attach. When our hair is cut, we do not feel any pain, the hair does not bleed, and when it is pulled, not a single muscle is stretched. And yet ... hair is a living substance capable of self-reproduction. Living cells that multiply at a tremendous rate are located in the hair root, which lies deep in the dermis.

The hair follicle is the hair root with the surrounding tissues that form the outer and inner root sheaths and the hair-glandular complex (sebaceous and sweat glands; hair lifting muscle; blood vessels and nerve endings). We are born with a certain amount such follicles, this value is genetically programmed, and nothing can be changed here. Although, perhaps, in the near future, scientists will be able to reprogram this hereditary information - now all the prerequisites have been created for this.

At the base of the follicle, and the dermis, there is a hair papilla - a connective tissue formation containing blood vessels. It provides nutrition and growth activity of the hair follicle.

Each hair follicle has its own innervation and muscles. Thanks to the muscles and nerve endings, the hair follicle has tactile sensitivity, allowing it to make subtle movements.

When the corresponding muscle - the muscle that lifts the hair - contracts from fear or cold, the hair rises and squeezes the skin, forming bumps or so-called " goose bumps". The blood vessels surrounding the hair follicle and hair papilla supply them with all the substances necessary for cell multiplication and hair growth. distinctive feature hair is that the rate of division of their cells in the human body takes second place after the rate of cell proliferation in the bone marrow.

Each hair follicle is an independent entity with its own growth cycle. In different follicles, these cycles are not synchronous, otherwise all our hair would fall out at the same time, while this process proceeds gradually and imperceptibly.

Hair is made up primarily of keratin, a protein built from amino acids. Some of these amino acids (cystine, methionine) contain sulfur atoms (we will return to this information when we consider the structure of hair).

Exemplary chemical composition healthy hair is like this:

• 15% water,
• 6% lines,
• 1% pigment,
• 78% protein.

If the hair has been exposed to chemical or physical influences, if certain diseases are found, the composition of the hair may change. For example, for frequent staining and perm, illiterate selection of hair care products, abuse of thermal styling methods, hair can lose a large percentage of moisture. In this case, it is necessary to select high-quality hair care products that restore normal level humidity.

Hair shaft

Each hair consists of a root (this is the part of the hair that is deep in the skin) and a shaft (we see it on the surface and this is what we used to call hair itself). There are three concentric layers in the hair shaft.

• The outer layer, or cuticle - it is also called the integumentary, scaly.
  The cuticle performs a protective barrier function... It is formed by six to ten overlapping layers of transparent keratin plates, interconnected by both numerous cross-links and lipid layers. The cuticle prevents mechanical and physical influences on the hair. An intact cuticle reflects light well; hair is shiny, elastic and does not break.
• Cortex, or cortex.
  The cortex is the main substance of the hair (80 to 85 percent of its volume), which consists of millions of keratin fibers. They are twisted together and connected by strong cross-links.
• The medullary layer is the central medulla.
  This is the central part of the hair shaft, which is not present in all types of human hair. For example, medulla is absent in vellus hair. Air bubbles fill the medulla - due to this, the hair has a certain thermal conductivity. Medulla does not play any role in changing both chemical and physical properties hair.

Hair structure and growth

Hair grows about 1 to 2 centimeters per month. The growth of new hair starts from the papilla, which is located at the base hair follicle... Cells divide and multiply inside the cortical substance (it is formed middle part bulbs) - this area, adjacent directly to the hair papilla, is called the matrix. As they move to the surface of the scalp, follicular keratinocytes gradually lose their nuclei, flatten and keratinize, filling with hard keratin (keratinized).

Among the cells of the hair follicle, melanocytes are also represented, which cause natural color hair. At the mouth of the hair follicle, a duct of the sebaceous gland opens, containing sebum, an oily substance that is secreted onto the surface of the scalp. Sebum along with exfoliated corneocytes of the epidermis and normal flora, it is the main protective mantle of the skin. It also lubricates the hair. giving them elasticity, smoothness and, to a certain extent, water repellency.

Hair life cycle

The life cycle of a hair consists of three stages; its duration ranges from 2 to 5 years. Each hair follicle is genetically programmed to produce approximately 25-27 hairs. Each hair lives according to its own "individual schedule", and therefore different hair at the same time are on different stages life cycle: 85% of hairs are in phase active growth(anagen), 1% in the resting phase (catagen) and 14% in the prolapse phase (telogen).

Anagen - continuous cell division in the hair follicle matrix, as a result of which new cells move to the surface skin scalp. This period of active growth lasts for 2-5 years.

Catagen - the division of matrix cells slows down and stops, the hair follicle "goes into hibernation". The hair follicle is gradually detached from the papilla. This phase does not last very long - about 3-1 weeks.

Telogen - cell renewal stops for about 3 months (the time during which the connection between the newly synthesized hair follicle and the hair papilla is restored, and new hair enters the anagen phase). The telogen bulb, completely detached from the dermal papilla, acquires elongated shape and begins to move to the surface of the scalp. During the telogen period, new hair begins to grow and the old one falls out.

On the scalp of each person, there are, on average, 100 to 150 thousand hair follicles, in which hair forms, grows and then falls out. Knowing the percentage of hair in different phases, you can calculate the value that characterizes the normal hair loss. Normally, we lose an average of 70-80 hairs per day.

Amino acids

Amino acids are building material for healthy hair growth. Essential amino acids other nutrients necessary for hair growth, enter our body with food. They are carried throughout the body by the bloodstream and through the capillaries reach the hair papilla. That's why long way to healthy hair and healthy skin lies through adhering to the correct balanced regimen nutrition.

A large number of amino acids, connecting with each other, form a polypeptide chain. The hair shaft is similar in structure to a rope or a three-core electrical cable. Polypeptide chains are intertwined to form threads. These threads, in turn, winding on each other, create a supercoiled structure: combining several pieces, they form first protofibrils of the hair, then microfibrils and, finally, the largest fibers - macrofibrils. Wrapping around each other, macrofibrils form the main fibers of the cortex.

Cross-links

Long polypeptide chains, located parallel to each other in the fibers of the hair cortex, bind to each other, forming transverse bridges. If it were not for these covalent bonds between certain amino acid residues of adjacent chains, the chains would separate and the fiber disintegrated. It is these cross-links that give keratin its unique qualities: strength and elasticity.

For example, disulfide bonds (bonds between two sulfur atoms) are the strongest, mainly due to the natural strength of the hair. The principle is based on the breaking and subsequent restoration of a certain percentage of these ties. perm hair.

Hydrogen bonds are much weaker than disulfide bonds, but there are much more of them. They are formed due to the mutual attraction of hydrogen atoms located on adjacent polypeptide chains. These connections play important role in providing hair elasticity.

If women dream of increasing the thickness of something, then it is definitely hair!

Scientific approach

An international team of scientists conducted a series of studies, which resulted in the following: only one gene is responsible for hair thickness. Experiments were carried out: first, 170 genes were selected, which were known to affect the properties of hair. Gradually, excluding genes, they found a pattern that was absent in some groups of people (by nationality) and was present in others - whose hairs just differ in thickness.

So scientists have determined that the protein receptor ectodislazin A is a gene responsible for the thickness of the hair, and that it (thickness) is laid at the stage of formation of the hair follicle.

So, first of all, the thickness of the hair depends on the race: the Asian ethnic group has the thickest and coarse hair, Africans have 30% thinner hair than Chinese and Japanese, and Europeans are half as thin as East Asians.

Hair Thickness Facts

• The thickness of the hair changes with age: in an adult, it is almost 3 times thicker than in a baby, but by old age it starts to thin again.
• Diameter female hair almost half as many as male. At first glance, this may seem strange. After all, some women bark for real luxurious hair! But in fact, it all depends on their density and length, and not at all on the thickness.
• Hair color can also tell a lot about hair thickness. The thickest hairs are for redheads, and the thinnest for blondes. Brunettes and brown-haired people most often have hair of medium thickness. It is, of course, about natural color your hair.
• Hair at the temples is thinner than at the back of the head. The same applies only to growing, so-called vellus hair.

Human hair thickness in numbers

By thickness, hair is subdivided into:

• Thin - less than 0.05 mm in diameter,
• medium - 0.05-0.07 mm,
• thick or thickened - more than 0.07 mm.

In micrometers (microns) thickness human hair ranges from 80 to 110 microns.

How to measure the thickness of your hair?

Exists different ways determination of this characteristic of the hair, for example, under a microscope. We offer a method for measuring thickness at home.

To do this, you do not even need to "torment" your hairstyle - it is enough to examine the comb or pillow after sleep.

Take one strand of hair or several, depending on the length of your hair. Wind the hairs around the pencil so that each subsequent turn lies close to the previous one, but not on it. It will be enough to wind the hairs half a centimeter-centimeter wide.

Count the number of turns and divide the width (remember, this is 0.5 cm or 1 cm: depending on the length of your hair) by the number of turns. This will be the thickness of the hair with a small margin of error.

The fact is that long hair at the ends they are thinned due to their dryness and split, and hair of different thicknesses is also found on the head.

How to increase hair thickness

How can this be done? After all, we have already found out that the diameter of the hairs is genetically laid. In fact, there are a few tricks for making your hair thicker.

Cosmetic procedure lamination

Hair lamination is intended just for thin and brittle hair.

A special composition is applied to their entire length, after which, under the influence high temperature there is literally "melting" of the balm into the core. As a result, each hair is enveloped in a film: it not only protects against harmful effects but also makes the hair thicker. This effect lasts up to 3 months, after which the procedure is repeated.

Special products with silicone

Silicone in composition special cosmetics acts by analogy with laminating agents: it takes up voids in open scales, envelops each hair, thereby thickening it. However, unlike professional procedure, silicone, alas, is not that useful.

Firstly, the effect lasts only until the first hair wash.

Secondly, silicone tends to accumulate, and as a result, after a while, the hair begins to "scream" SOS: and their bad condition by no means conducive to an increase in thickness!

Hair thickness masks

Homemade masks will help to achieve the effect of hair thickening. With their regular use, you will noticeably improve appearance your hair.

Gelatin mask

Dissolve 3 g of edible gelatin in a glass of water room temperature... After swelling, heat the gelatin in a water bath and bring the mixture until smooth. Add a few drops of your hair balm to the resulting composition. Perfect for these purposes.

Apply the mask to wet hair and leave it on for 40 minutes, then rinse with a shampoo for your hair type. The effect is similar to professional lamination, but to fix it, such a mask must be performed at least once every 2 weeks.

Colorless henna mask

Henna works well for hair roots: Iranian henna is believed to stimulate dormant hair follicles to grow, making hairs thicker and stronger.

To perform such a mask, you need to dilute 1-2 sachets of henna. warm water(temperature approximately 40-50 C 0) until a homogeneous mushy mixture is obtained. Apply the gruel to the hair - on the roots and along the length - and leave to dry completely. To prevent the henna from sprinkling, you can cover your head with a plastic cap and a towel.

After about 40-60 minutes, rinse the mask thoroughly with water, rinse your head with shampoo. Apply balm. With regular use of the mask, the hair will become noticeably thicker.

How to further increase the thickness of your hair?

Owners of a hair type that, for one reason or another, requires special care, it is often noted that an increase in hair thickness is often nice bonus impact aimed at treating them from loss or recovery after staining.

To thicken your hair, start with the following:

• Correct and balanced diet including in daily diet required amount protein, iron, calcium and vitamins for beautiful and healthy hair.
• Self-massage of the scalp, which activates the flow nutrients to the roots for the growth of thick hair.
• Moderate use styling products and devices, which, unfortunately, in addition to beautiful styling do not benefit your hair in any way.
• Regular trimming of the ends of your hair: this way you are guaranteed to get rid of their fineness and splits.
• Hair care using the right means... This is very important, because if shampoo or rinse is not suitable for your hair type, and there can be no question that the strands please you with density and volume. care is available in the ALERANA ® line - series No. 1 against hair loss and to stimulate hair growth.

Hair is not only a human decoration. According to them, the identification of personality, gender, and sometimes social status... Therefore, everyone strives to have strong and healthy strands. Knowing the structure of the hair and scalp, the peculiarities of nutrition and life, it will be possible to provide proper care for your curls and make them strong and beautiful.

The skin covers the entire human body. In the head area, it is represented by three layers:

• Epidermis
• Dermis
• Adipose tissue

1. The epidermis (the so-called cuticle) has a thickness equal to several tenths of a millimeter, despite the fact that it is represented by a considerable number of cells. The basis of this layer is made up of living, full-fledged cells. Horny scales represent the outer layer. Dying off, they peel off, but new ones are immediately formed in their place. Thus, the update is carried out.
   The function of the epidermis is to protect the human body from unwanted environmental influences.
2. The dermis is the middle layer of skin made up of countless strong elastic fibers. There are muscles and blood vessels, sebaceous and sweat glands, as well as follicles and roots of the strands. Thanks to this layer, the skin is characterized by a certain elasticity and tone.
3. Fatty tissue is the last layer, subcutaneous. In this area is the base of the bulb through which the curls feed.

What is human hair made of?

Human strands have certain physical indicators. It is about strength, elasticity, electrical conductivity, ability to absorb moisture, resistance to different kinds negative external stimuli. All these qualities are possible due to the peculiarities of the composition and structure of the curls.

Rod and follicle

The rod is the part visible to our eyes. It protrudes above the surface of the skin and consists of keratinized cells. A feature of the rod is the ability to stretch by 1/5 of its size and not feel pain.

A follicle, or hair follicle, is hidden inside the skin. It is "alive" and is responsible for the growth of the strands. It is into it that the channels have an exit sebaceous glands, giving shine and elasticity to curls. Minor selection this secret leads to the fact that the curls look dull and lifeless. Conversely, the function of the sebaceous glands can be excessive, as a result of which the hair quickly becomes greasy and dirty.

In addition, 3% of human hair consists of water, and 97% is keratin.

Keratin, a protein built from amino acids, is the main building block for strands. It boasts the content of various microelements: copper, zinc, chromium, manganese, iron, as well as vitamins A, B, P, C, T, etc. The health of the curls directly depends on how much the human body has enough of these vitamins.

The chemical composition of healthy hair is roughly the following:

• Carbon (about 50%)
• Oxygen (about 20%)
• Nitrogen (about 17%)
• Sulfur (approximately 6%)

The chemical composition of the strands can change, depending on whether the curls were exposed to chemical and physical influences, or in the case of detection of diseases.

Structural features

Hair is a special form of skin inherent in representatives of the mammalian world and humans. A significant part of the surface of the head is covered with this kind of threadlike formations.

Follicle structure

Each hair grows out of a personal follicle, a kind of matrix for cell growth. The curls will grow in length only as long as their roots function.

The follicle looks like a small indentation containing a root that is shaped like a pouch. Downward, it is somewhat expanded, forming a hair follicle, to which blood vessels, sweat and sebaceous glands... They are responsible for the nutrition and elimination of waste products of the strands.

The nourishment of the hair follicle is possible thanks to the vessels that fit the papilla. It is located at the very base of the bulb. If hair falls out, then only together with the bulb itself.

Hair shaft structure

The hair shaft diagram clearly demonstrates all of its features.

Looking at the structure of the hair with a microscope, three main parts can be clearly seen:

• Cuticle
• Cortex (cortex)
• Medulla (medulla)

1. The cuticle is the layer on the outside. It is based on keratinized scales, placed on the principle of shingles, by overlapping each other. The location of the scales is fixed, in the direction from the roots to the tips. The main function of the cuticle is to protect the curls from outside influences. Each cell of this layer contains a fatty acid, which gives the strands a water-repellent effect. Also, thanks to her, the scales are closely adjacent to each other. Fatty acid cannot be removed by regular wash hair, but it can be easily damaged by chemical influences.
   The porous or vitreous structure of the hair is determined by the properties of the cuticle. Porous strands are dry, brittle, and quickly absorb dirt and chemical components. The vitreous structure of the curls is elastic and dense.
2. Directly under the cuticle is the cortical layer - the cortex. He is responsible for keeping the curls elastic. The strands will be straight or curly from the structural features of this part. The fact that the cortesque is well developed explains the ability of the hair to curl or stretch. If the cortical layer is insufficient, the strands begin to break.
   It is the cortex that is 90% keratin. The remaining 10% is accounted for by melanin, the pigment responsible for determining the natural, natural shade. In addition, it is in this layer that air bubbles are located, which have the property, mixing with the pigment, to give the hair a variety of shades.
3. In the very center is the medulla - medulla. However, in very fine hair, it may be absent. In animals, this layer provides thermoregulation. In humans, this function of the medulla is absent due to the voids it contains.

Damage to the central layer leads to the death and loss of the hair. But a new one grows in its place.

As far as a person has a developed medulla, his hair will be voluminous and strong. This easily explains why it can be so difficult to grow thick hair without having a genetic predisposition to this.

What are the functions of hair

The main functions of hair:

• The protective function is that the hair prevents the penetration of ultraviolet radiation onto the skin when exposed to direct sunlight.
• Thermoregulation. It's hard to believe, but it was the hair that protected a person from colds in those days when it did not exist. warm clothes... When cooled, they rise, thanks to the erector muscles, and retain their own heat from the skin.
• The tactile function is determined by a large number of nerve endings in the scalp, as a result of which its sensitivity increases even to minor changes in the position of the hair. This can be seen especially well when an insect crawls over the head.

Hair structure and growth

Within a month, the strands can increase in length by 1-2 cm. The growth of a new hair originates from the papilla located at the base of the hair follicle. Cell division and multiplication is carried out in the cortex. As it moves to the surface layer of the scalp, the hair thickens, keratinizes and fills with hard keratin.

Among the cells of the hair follicle there are special ones - melanocytes, which are responsible for the natural shades of the hair.

At the mouth of the hair follicle, the ducts of the sebaceous glands have an outlet. The oily substance released flows onto the surface of the scalp and lubricates the curls, leaving them smooth, supple and radiant.

To have healthy, beautiful curls everyone is capable. One has only to study the structure of human skin and hair, and on this basis, provide them with proper care and nutrition.

Hair structure and types

Hair.
Hair structure and types

Navigation through the article:

Human hair function

Biological function hair- protective. Hair on the head, prevent it from overheating and protect it in cold weather, as well as from mechanical impact(blow). Eyelashes protect eyes from foreign bodies (dust particles, dirt), and hair in nostrils and ears intercept foreign bodies and prevent them from entering the body. Brows protect the eyes from sweat.

Hair structure

The approximate composition of healthy hair:

• 78–90% squirrel(keratin)
• 6% lipids(fatty acid)
• 3–15% water
• 1% pigment

The main chemical elements in hair are:

• carbon (49.6%)
• oxygen (23.2%)
• nitrogen (16.8%)
• hydrogen (6.4%)
• sulfur (4%)
• in microscopic amounts: magnesium, arsenic, iron, phosphorus, chromium, copper, zinc, manganese, gold.

The hair consists of two enlarged parts:

• Kernel- the outer, visible part of the hair protruding above the surface of the skin.
• Root (follicle)- a part of the hair located inside the tissues of the skin with the surrounding tissues and including the hair-glandular complex (sebaceous and sweat glands; muscle that lifts the hair; blood vessels and nerve endings)

Hair shaft

The outer (visible) part of the hair - the shaft, mainly consists of a horny protein substance - creatine.

Blood does not enter the hair shaft, there are no nerve endings in it... Therefore, when cutting, we do not feel pain, the hair does not bleed.

The hair shaft consists of:

• cuticle- the outer part of the rod, consisting of 6-9 overlapping layers of cells of transparent amorphous keratin, resembling scales in structure (like in fish or pine cone). The space between the scales is filled with lipid sheets (fatty acids), due to which the scales adhere tightly to each other. The scales are directed from the hair root to its tip.

  Cuticle function mainly protective, which protects the cells of the inner layer of the hair shaft (cortex) from water, sun and mechanical stress.

• cortex- the inner layer of the rod, consisting of keratin (protein) cells, which have not yet been completely keratinized (keratinized), glued together by keratinized fusiform cells. The cortex makes up 80 to 85% of the total volume of the hair shaft. Like any other protein, keratin is made up of amino acids that form polypeptide chains that intertwine to form strands. These filaments, in turn, fastening together several pieces, form first protofibrils of the hair, then microfibrils and, finally, the largest fibers - macrofibrils. Macrofibrils, held together by fusiform cells, constitute a cortex that makes up 85% of the hair shaft structure.

  The main function of the cortex- This is shaping the hair, maintaining the elasticity and strength of the hair.

  Due to the peculiarities in the structure of this layer, people can have straight or curly hair, which in turn are genetically inherited.

• medulla(central medulla) is the central part of the hair shaft, composed of keratin-based keratinous cells and containing voids filled with air. Medulla in humans is not present in all types of hair, for example, medulla is absent in vellus hair. Marrow cells contain glycogen and may include melanosomes. Medulla is filled with air bubbles - due to this, the hair has a certain thermal conductivity. Medulla does not play any role in changing both the chemical and physical properties of the hair.

Hair root (hair follicle)

The subcutaneous part of the hair (root or follicle) consists of:

• outer root sheath(external epithelial vagina)
• inner root sheath(internal epithelial vagina)
• bulb(hair papilla)
• sebaceous gland
• levator hair

Man is born with already formed number of follicles and for each person, this amount is individual and is inherited from the parents at the genetic level.

In addition, the number of hair follicles differs in people with in different colors hair. On average, the total number of hairs on the head:

• blondes - 140 thousand
• brown-haired - 109 thousand
• brunettes - 102 thousand
• redheads - 88 thousand

It is in the hair follicles that hair begins to grow.

The rate of cell division in the hair follicle ranks second in the human body after the rate of cell division in the bone marrow. Thanks to this, hair grows about 1–2 centimeters per month.

Hair color

Among the cuticle scales, and among the rods of the cortex layer, there are pigment granules in the form of melanosomes, which give the hair a certain color... The shade of the hair is determined by genetic factors and depends on the ratio of the content of the two main pigments: eumelanin(black hair) and pheomelanin(Red hair).

Thus, hair color depends on a combination of two factors: the ratio of pigments and the number of pigment cells in the hair structure.

Hair types

The condition of the hair itself depends on the intensity of the work of the sebaceous glands of the scalp. The higher the secretion of sebum by the glands, the higher the fat content of the hair itself.... Sebum spreads over the entire surface of the hair, covering it with a thin film. Depending on the "fat content" of the hair, they are divided into four types:

• greasy hair (increased hair greasiness)

• are characterized by increased oily sheen
• stick together in separate strands
• elastic
• more often thick

• quickly get dirty and lose their attractiveness
• cause difficulties when doing hairstyles
• do not electrify

• dry hair(reduced hair greasiness)

• have a dull appearance
• difficult to comb and tangle
• split ends
• strongly electrified

• normal hair(normal functioning of the sebaceous glands)

• moderate, healthy shine hair
• obedient when combing
• flexible and elastic
• no split ends
• do not electrify

• mixed hair type (fat roots and dry split ends)

• hair looks dull and lifeless
• fatty at the roots
• brittle, starting from the middle of the hair
• the ends split
• weakly electrified

• hair roots begin to form at the end of the third month intrauterine development fetus
• on the head, hair does not grow evenly - more densely on the crown of the head, and less often on the temples and forehead
• an adult has an average of about 100 thousand hairs on his head
• hair grows by 1 mm on average in three days (i.e. by 1 cm per month)
• v summer time and hair grows faster during sleep
• the rate of hair loss is from 60 to 120 pieces per day. In place of the falling out, new hair begins to grow, from the same hair follicles.

As is known, the best decoration any woman is her hair. According to their structure, they are different: for some they are thin and brittle, and for others they are thick and elastic. The structure of the hair largely depends on its composition. Let's consider in more detail what the hair consists of.

Hair structure

Hair usually consists of a visible and invisible part. The visible part of the hair is the shaft, invisible, immersed in the scalp, it is the root. Bottom part the root contains a small papilla, which consists of blood vessels and nerve endings. This papilla has a nourishing function to promote hair growth.

The hair root is anchored in the so-called hair follicle - the follicle. Thus, the density of the hair depends on the number of follicles in the scalp. Since the number of follicles is at the genetic level, the density of human hair is determined from birth. Usually in women with blond hair there are about one hundred and fifty thousand hairs, and women with red hair have eighty thousand hairs. The number of hairs at the temples and forehead is significantly less than at the crown of the head.

The deepest and widest part of the root is the bulb. The place of coincidence of the exit of the hair to the surface with the exit of the sebaceous glands surrounding given hair, is called hair pore. Thanks to the sebaceous glands, the elasticity of the outer part of the hair is maintained. When secretion from the sebaceous glands to insufficient quantity the hair becomes dull and brittle.

The hair root and the surface of the skin are connected by a small hair muscle, adjustable nervous system... When the hair muscle contracts, the hair becomes upright. This process most clearly expressed in a person with fright.

As for the hair shaft, it includes three layers: outer, middle and last (outer). The outer layer of the hair shaft is called the cuticle. It consists of seven or nine rows of corneous plates, which are arranged in the form of tiles. The middle layer of the hair shaft is called the cortex. It performs the flexible and elastic function of the hair, and the melanin pigment content gives the hair saturated color... With the aging of the human body, this pigment gradually disappears, which causes the appearance gray hair... The last layer of the hair shaft is called "medulla". It contains incompletely keratinized cells. If a person has very Thin hair, then in such hair there may not be the last layer of the hair shaft. We told you what hair consists of, and now we will take a closer look at its chemical composition.

The chemical composition of the hair

The chemical composition of hair is characterized by the presence of carbon, oxygen, nitrogen, hydrogen and sulfur. The main constituents of hair are melanin and keratin. Thanks to keratin, keratinization of hair cells occurs, and the presence of melanin in the composition of the hair ensures their color saturation. Hair also contains substances such as cholesterol, minerals and arsenic.

When the process of functioning of the active cells of the papilla is inhibited and completely stopped, the dead hair is replaced with a new one fresh hair... Thus, the bulb is pushed outward, which entails hair loss. Thanks to the formed new active cells in the hair follicle, the life of a new hair is born. Normal natural process hair change is characterized by a loss of 30-50 hairs per day.

With all this, it should be remembered that any hair requires careful maintenance. The better we take care of them, the longer they will delight the eye with their good structure and rich color!