Anyone wants to have beautiful thick strands, but not everyone cares about their health. The growth, morphological structure and life cycle of our curls will be discussed further.

human hair structure

What is hair

The follicle is a root combined with connective tissues, together they form a single glandular complex, as well as the internal and external vagina.

Each person is born with a clearly established number of hair follicles; it is impossible to change it.

The so-called “hair papilla” is located in the structure of the scalp - this is an element connective tissue, which contains blood vessels.

Each of the hair follicles located on the head or body of a person has its own muscles and innervation. Due to the fact that the structure of the hair is this way, it can move slowly and barely noticeably.

Any follicle is a completely autonomous formation, it is characterized by individual independent development and growth. The successive cycles in which the strands are changed are not the same, so the process of hair renewal does not occur so noticeably and gradually.

Human hair has a number of physical properties:

• they can absorb moisture;
• strength;
• electrical conductivity;
• elasticity;
• resistance to various negative impacts from outside.

Structure

What is the structure of human hair? Basically, these formations consist of a component such as keratin: this structural element protein nature, which is based on multiple amino acids.

Healthy human hair has this chemical composition:

• it consists of 15% water;
• 6 percent are lipids (fat cells);
• pigment occupies only 1%;
• The main structural component of hair is protein (keratin). It accounts for 78% of all elements in the structure of our strands.

The growth and development of the hair follicle may be subject to changes due to physical, chemical influences from the outside or in the presence of certain chronic diseases internal organs or scalp.

In addition to keratinocytes (“building” cells), the structure of curls also contains melanocytes – they are “responsible” for the color of our curls.

At the base of the hair are located sebaceous glands, they are entrusted with the function of synthesizing the required amount of sebum, which is released onto the surface of the scalp. It is this oily substance, in combination with exfoliated particles of the scalp, that performs the task of maintaining local normal flora.

Sebum also nourishes our curls, lubricates them, and has the ability to repel water.

Any healthy hair is constructed from the following parts:

• root (located deep in the scalp);
• the shaft (the hair itself, it consists of three structural layers).

The elements of the hair follicle are:

• the medullary layer is a medulla that is not present in all types of hair (for example, in vellus hair such a layer is completely absent);
• cuticle is the outer layer of hair (its other names are scaly, integumentary). The cuticle has a protective function. Basically, this hair layer consists of keratin molecules that prevent chemical and physical trauma to the hair shaft.
• Cortex (cortical layer) is the basic component of the hair follicle. Its specific gravity is at least 85% of the total structural volume of the hair. This layer consists of many keratin molecules carefully intertwined with each other.

How hair grows

How fast does hair growth occur? U healthy person The length of curls increases by an average of one to two centimeters per month. This process begins with the hair papilla, then structural cells multiply in the cortex, then keratinocytes get rid of their own nuclei, gradually become keratinized and over time are completely filled with keratin.

The growth and development of a new keratinized formation occurs over a period of two to five years. This time period is called the “life cycle”.

Any hair follicle over the entire period human life produces from 25 to 27 formations. After completing your life stage all hair falls out, and new ones begin to grow in place. This process is called “cycle change.”

Stages of hair development

As mentioned above, the growth of strands on a person’s head is cyclical. Its structure includes the following sequential stages:

• anagen is a long phase during which active hair growth occurs and the scalp is intensively nourished;
• catagen is a short period, the formations stop growing, the melanin pigment is not produced, the base of the follicle gradually moves towards the surface of the skin;
• telogen – the duration of the stage is on average three months, old hair falls out and is replaced by new keratinized formations. This stage ends life cycle hair

Typology

Growth and development are observed on the human head various types hair formations. There are three of them:

• bristly - human eyelashes and eyebrows are made up of them;
• vellus - located on the limbs and body;
• long - growing on the scalp, as well as being part of the beard.

The total number of follicles in the scalp varies from person to person.

For example, the scalp of brunettes has at least 100,000 hairs, but blondes have more intense hair growth - their number can reach 150 thousand.

Interestingly, the number of hair follicles varies across different parts scalp: thus, the parietal zone is covered with hair more densely - there are up to 350 thousand bulbs per 1 cm2 of area, but the occipital and temporal areas are more “bald”: total number hair here does not exceed 250,000 units per square centimeter.

According to statistics, a person’s hair can be colored in more than fifty shades.

There are eight primary colors:

• ashen;
• light and dark brown;
• light brown;
• dark and light chestnut;
• black.

What does hair color depend on? A certain shade of a curl is determined by the amount of melanin (coloring pigment), its type and the nature of its placement.

Melanin is a protein formation that contains some sulfur, nitrogen, arsenic and oxygen.

Hair pigment is contained in granular and dispersed forms in the cortical layer of the hair. In this case, each of the substances performs its function:

• “granular” melanin gives the curls a red and black color;
• “scattered” pigment colors the strands yellow or reddish.

It is clear that the color of a person’s hair directly depends on the proportions of the various substances of the melanin pigment.

Types of damage

Under the influence of negative external factors healthy hair can be damaged.

Trichologists distinguish four types of main hair shaft defects:

• fractures that form due to mechanical damage;
• hair fragility due to disruption of its shape;
• twisting of formation;
• the action of foreign chemicals.

Accordingly, many people have a question: how to restore hair structure? The technology of the process depends on the problem faced by the person. Let's consider options on how you can change damaged hair structure:

• premature gray hair – it is necessary to use shampoos designed for dry curls; the use of leave-in balms and conditioners is indicated; Care products containing keratin should be used.
• Consequences of chemotherapy - during the recovery period it is not recommended to carry out the staining procedure; It’s better to cut your hair short; It is necessary to use care products for sensitive scalp.
• Abuse of dyes or cosmetic procedures - it is better to cut off damaged hair; deep conditioning; treatment courses using protein (protein) drugs; intensive hydration of hair and scalp; effective nourishing masks.
• Hormonal dysfunction in the body - intake medicines that improve the structure of curls (Finasteride or Minoxidil); laser correction; taking biotin; regular use of conditioners that nourish the strands.

The following cosmetics help to qualitatively change the structure of curls:

• masks enriched with vitamins and amino acids;
• shampoos with exfoliating effect;

Structure and physiology of hair.

Hair is usually called "appendage" of the skin- these are horny formations located almost

over the entire surface of the human body. Hair health depends on the balanced functioning of the entire body, especially the digestive system.
They are quite strong and elastic, capable of stretching by 1/5 of the total length and returning to their original state. Ropes from women's braids that were woven during Kievan Rus, were so strong that they were used to lift heavy loads.

Hair quickly absorbs water and tolerates a slightly acidic environment, but alkaline compounds are harmful to it. For example, during chemical straightening, their structure is destroyed, since NaOH - (strong alkali) is used for such procedures. Hair has the ability to accumulate substances; criminologists take this factor into account and use it in their work. Vellus hairs serve as tactile receptors and protect against dust in the ears and nose.
Hair can hardly be called a living substance. When we do a haircut, we do not feel pain, since the hair is not supplied with blood and is not touched nerve endings. However, hair is capable of self-reproduction. The cells located in the hair root divide at a high speed, due to this their growth occurs.
The hair shaft is the part that is located above the skin. The hair root, located in the hair follicle, is hidden deep in the dermis and ends in the hair follicle. The follicle consists of connective and epithelial tissue. The hair follicle is nourished through the hair papilla, which carries blood vessels. On top is the layer of Henle - a row of keratinized cells devoid of nuclei.

Ducts are open into the hair follicle sebaceous glands. In the area of ​​the mouth, the cells of the outer layer are scaly in nature and, disintegrating, mix with the sebum of the gland, gradually become nuclear, and due to their active division, hair growth occurs. It is worth noting that the rate of reproduction of hair cells is in second place, after the reproduction of cells in the bone marrow. Around the hair follicle, or in other words, the hair root, there are tissues that form the internal and external root sheaths. Each follicle has a muscle that fixes the hair. If a person feels cold or has a feeling of fear, the muscle contracts, the hair rises and compresses the skin, forming goose bumps. The hair shaft fixes not only the muscle, but also blood vessels and nerve endings. The number of hair follicles varies from person to person, with genetics being the determining factor.

Each hair follicle has its own growth cycle. These cycles are uneven in different follicles. Otherwise our hair would fall out in an instant.

The hair shaft consists of three concentric layers: The central part of the hair is filled with medulla, between the cells of which there is air - this part is called the medula. The medulla does not contain vellus hairs and the ends of other hairs. For physical and chemical properties hair medula has no effect.
The cuticle is a scaly layer that covers the hair, protects it from various environmental factors, and prevents mechanical damage to the hair. It consists of 7-10 overlapping transparent keratin plates, secured to each other by lipid layers and transverse ligaments. If the hair cuticle is not damaged, the hair looks shiny, elastic and not brittle.
The cortex is the basis of the hair; 85% of its volume consists of a large number of keratin fibers. They are intertwined and firmly connected. The cells of this layer contain pigment: yellow, black, red. The predominance of any pigment determines the hair color. In relation to the surface of the skin, hair grows under different angles from 10% to 90%.
A small growth angle makes it difficult to style your hair and, in addition, there is a possibility that the hair may grow into the skin, which will lead to inflammation.
Each hair is equipped with smooth muscles, one end of which is attached to the dermis, the other is located below the mouth of the sebaceous gland. If the muscle contracts, the hair rises, while the sebaceous gland contracts and its secretion is released. Sebum resembles an oily substance that lubricates the hair and creates a water-lipid film that performs a protective function. The pH level of the film is 4.6-6.5 (slightly acidic environment), thanks to this factor there is no proliferation of microorganisms on the skin.

The water-lipid film has a water-repellent effect, i.e. prevents dryness of the epidermis and protects against UV rays.

Chemical composition of hair.

We already know that the basis of the hair is the cortex, which is formed from many keratin fibers. Keratin is a protein (organic substance) consisting of amino acids and rich in vitamins (B, A, C, D, P) and microelements (zinc, manganese, iron, copper). The amino acids methionine and cystine contain sulfur, which is involved in the process of protein synthesis, due to which hair growth occurs.
Healthy hair should contain at least 6% lipids, 78% protein, 15% water and 1% pigment. A common hair problem is dryness and brittleness, this is due to loss of moisture, i.e. with changes in the chemical composition of the hair. The reasons can be various, from incorrectly selected cosmetics to abuse of thermal hair styling methods.
The path to healthy hair and skin lies through complete, proper nutrition. Amino acids are the main building material which our body receives from food. Amino acids reach the hair papilla through the blood through capillaries. As a result of the reaction, groups of amino acids interact with each other to form a polypeptide chain. In turn, the polypeptide chains, intertwining with each other, create threads that form a complex helical structure. Similar structures, combining into several pieces, create protofibrils, then microfibrils and the largest fibers - macrofibrils. They form the basis of the cortex, intertwining with each other.

The polypeptide chains in the fibers, located in parallel, are connected to each other by covalent bonds (cross bridges). If not for this connection, the chain would lose strength and the fiber would disintegrate. The strongest bonds are disulfide bonds (the bond of 2 sulfur atoms) - this is what ensures the strength of the hair. Hydrogen bonds are responsible for their elasticity. They are less durable than disulfide ones, but there are more of them. They are formed due to the attraction of hydrogen atoms located on parallel peptide chains.

Hair development and growth.

The first hair appears on the forehead already in the third month of fetal development. First, a protrusion forms on the lower surface of the tissue epithelium. Next comes the process of cell separation. The axial cells form the substance that makes up the base of the hair, and the inner epithelial sheath is the follicle. Thus, the formation of vellus hair rudiments occurs throughout the body; they emerge to the surface already in the 5th month of intrauterine life.
In the first year, hair renewal occurs several times. Hair color also changes and only in adolescence acquires a constant color range.
Hair can be classified depending on the change of “generations” into primary (vellus and prenatal) and secondary (terminal and intermedial). Terminal ones, in turn, are differentiated into bristly - eyelashes, eyebrows, as well as hair in the ear and nasal passages) and long (in the male half of humanity - mustache, beard, in addition to the groin area, scalp and armpits.
Vellus and prenatal hair, as a rule, they are devoid of pigment and brain matter, their length is no more than 2 cm. In a child, vellus hair covers the entire crown of the head only in the 3rd year of life, and thick intermedial hair forms on the head. Secondary hair, depending on nutrition and climate, may have a greater or lesser amount of pigment from light to black. In men, vellus hair is most often replaced by long, pigmented hair, especially in the chest and arms. By structure long hair also differ, they can be wavy, straight, curly.
Terminal hair growth depends on several factors - racial, hormonal, constitutional. In the first years of life, vellus hair grows in a person, then the hairline is replaced, and stronger, thicker hair with pigment is formed; they are classified as intermedial. Terminal or secondary appear during puberty. This hair may have some differences in color and shape from the hair of the previous generation. The change of hair to secondary hair also occurs in the area of ​​the external genitalia, in the armpits, and in the male half of humanity on the arms, legs, face and back.

On the face, the change from vellus hair to terminal hair begins from the lateral areas of the upper lip, then on the chin and cheeks. In the eyebrows, nostrils, and eyelids, bristly hair is formed during the same period.
At the age of 15-16 years, 100% of men and 80% of women complete the change from vellus hair to terminal hair. This process is associated with the formation of bald patches in men on the forehead and temples. If we compare the intensity of hair growth in the opposite sexes, in women growth occurs at a rate of 0.7-1 mm per day, it grows faster in the warm season, in men - 0.5 mm. Hair tends to grow in a certain direction and is distributed in threads. Hair grows most intensively in the period from 15-30 years, but these figures are not entirely clear, since everything depends on the degree of care and nutrition. After 50 years, their growth slows down. The bristly hair in the eyebrows grows slowly throughout life.
At the age of 5, a child’s eyelashes are the same length as an adult’s. On the head, most hair is located in the crown area, less on the forehead and temples. In children, hair change occurs faster; on average, the lifespan of hair is 3-4 years. In an adult, hair length can reach 60-70 cm; 1 m or more is very rare, most often in girls under the age of 18.
Hair change occurs every 5-7 years. In men, the life cycle of hair is less than 2 years. The thickness of the hair of brunettes, blondes, and brown-haired people is different. On average, the diameter of European hair is from 50-105 microns. Red hair has the largest diameter of 100 microns, brunettes 70-75, blondes - 50-60 microns.
The hair is much thicker on the beard and in the genital area. Their diameter ranges from 120 to 140 microns, in intimate places in women 130-150 microns. The depth of hair roots depends on age, so there may be differences. Cannon - 1.5, 2 mm, long (secondary) have a depth of up to 5 mm.

Phases of hair development.

The cycle of hair growth and development can be divided into 3 phases:
1. The initial phase of formation and active growth of hair (Anagen).
2. Transitional phase - the hair follicle stops working (Catagen phase).
3. The hair development cycle stops - the calm phase (Telogen phase).

Every hair, regardless of type, goes through this development cycle. With age, hair becomes thinner, grows slower, loses pigment, and its growth and development cycle is shortened. This process does not apply to the growth of eyebrows and hair in the ear canal area in men; rather, on the contrary, they thicken throughout life. The duration of the hair change cycle lasts several years, then the resting phase begins (telogen 100 days), the old hair falls out, and a new life cycle begins again, the duration of which is from 3 to 5 years.
A hair follicle is capable of producing about 25 hairs. Each hair has its own specific stage of the life cycle. Approximately 85% is in the stage anagen (active growth), only 1% has the catagen stage (resting phase) and the remaining 14% is in the stage telogen (loss).
Anagen is a continuous process of cell division in the follicle matrix, resulting in new cells moving towards the surface of the scalp. On average, active growth lasts 1000 days (from 2-5 years).
Catagen is the gradual cessation of cell division. The hair follicle loses its connection to the hair papilla. This period is short-term, lasting about a month.
Telogen - cessation of cell renewal. The period during which the connection between the hair papilla and the newly formed bulb is restored again, the new hair enters the phase of active growth (anagen). The duration of the period is about 3 months. The telogen bulb takes on the shape of a flask, becomes elongated and gradually moves towards the scalp.
During the telogen period The hair does not fall out immediately; as it grows, nutrients from the papilla stop flowing into the bulb, and its cells become keratinized. The process of hair loss lasts for 2-3 months.

If you pay attention to the root of a lost hair and find a notch or dismemberment in it, in this case the hair is pathological. As a rule, it is weak and breaks easily once it reaches the surface of the skin. In an adult, the anagen phase of hair depends on its location. For example, for eyebrow hair, the growth phase lasts 5-8 weeks, and the telogen phase (loss phase) lasts 3 months. On the back of the hands - anagen lasts up to 10 weeks, telogen (6 weeks). Eyelashes (life expectancy 4-5 months), vellus hair live up to 10 months.
Many balding people experience hair loss no more often than others. The fact is that new, healthy hair does not form at the site of loss. In case of violation endocrine system Some hormones affect hair growth. Cortisone and estrogen, female hormones, promote the onset of the anagen phase. The male hormone androgen prolongs the growth period.
Hair growth process is a set of chemical reactions. The follicle contains up to 7 various types cells that interact both with each other and with blood and nerve cells. Hair growth depends on many factors. Proteins play a primary role and must be present in certain concentrations and groups. Their absence leads to the cessation of hair growth. In the follicle, cells from the remainder of the germinal layer begin to actively multiply, as a result of which the atrophic papilla thickens. The mother cells of the hair follicle synthesize new epithelial layers, which gradually form a new hair follicle.
The physiological process is repeated several times, but with each change the follicle rises slightly upward. Therefore, the newly formed hairs sit less deeply. In this regard, you need to pay more attention to them if you want to preserve their beauty.

Hair growth is a continuous process and depends on the time of day; during the day, it grows faster than at night; in autumn and spring, its growth intensifies compared to other seasons of the year. The average hair growth for an adult is 15 mm, for children - 13 mm, for old people - 10-11 mm. Hair speed decreases depending on condition nervous system, food quality, work endocrine glands. There are 100 thousand or more follicles on the human scalp. Normal hair loss can be calculated by knowing percentage hair phases The normal rate of hair loss is 75-80 per day.

Quantity and color. There is a direct relationship between skin and hair; the thinner the skin, the thinner the hair. Their number also depends on the thickness. Blonde (brown) hair in diameter is 0.04 mm, black - 0.05 mm, red - 0.07 mm. Accordingly, the amount of hair is also different. Blondes have on average up to 140 thousand hairs, brunettes have up to 100 thousand, brown-haired people have even less, even up to 30 thousand. Of course, the density of hair in different areas differs, most of them are on the scalp, especially on the top of the head. The hair density is least on the back of the hands and feet. Hair can grow from the skin at different angles, including perpendicularly. Let's look at the factors that determine hair color. Skin and hair color are closely related and depend on the degree of production of melanin (pigment) by melanocyte cells. Melanin forms different shades of red, black, white, gray.
There are two types of melanin.

1) Pheomelanin (yellow and red) color.
2) Eumelanin (brown and black) color.

The content of granules of this pigment in the cortex determines the color of the hair. As a rule, the granules have an elongated shape, but there are round and oval ones; they determine the color of the hair. Large quantity elongated melanin granules make hair black, the fewer of them in the cortex, the lighter than hair. If large number elongated granules are combined with round ones, in this case the black color hides the red one, but a slight red tint appears. Combining oval granules with a medium number of elongated ones gives the hair a rich brown with a red tint.
Silver-gray hair appears in middle age due to a slowdown in pigment formation. When melanin synthesis stops, all hair becomes colorless, in other words, gray.
White hair grows in the complete absence of melanin granules; in addition, natural hair differs in color, since melanocytes are not equally active. Also, hair and eye color are closely related. For example, those with burning black hair tend to have brown eyes. Brown-haired women have light skin because they produce a completely different coloring substance. Special attention Always pay attention to the appearance of the hair; its health depends on the condition of the cuticle. In case of cell loss, their tile-like arrangement is disrupted, this is the cause of hair and its fragility.

Hair shape. The structure of the hair consists of intertwined polypeptide chains, connected by cross bridges and covalent bonds, ensuring the strength of the hair. The elasticity of the hair depends on the amount of water in the intercellular substance and keratin fibers. The shape of the hair depends on the person’s race. Mongolians have straight, hard-to-style, coarse hair. Representatives of the Negroid race have curly, thick hair. Europeans have soft and fine hair. Hair of individual people race may also differ, but they have common features.
Europeans have an oval cross-sectional shape of hair, which is why they can form curls. Asians have thin and round hair, so it grows straight. African Americans have flat shape hair, in the form of a ribbon. The structure of the hair shaft depends on the shape of its root, i.e. curly hair grow from C-shaped hair follicles, straight hair grows from a straight hair follicle. Of no small importance for the shape of the hair is the exact composition of keratin, which can change throughout life.
There are 3 main hair forms, which are divided into subtypes.

1) Wavy-haired (subtypes: curly, narrow-wavy and wide-wavy). The cut shape is oval.
2) Smooth-haired (subtypes: tight, smooth, flat-wavy). When cut, they have the shape of a circle.
3) Curly-haired (subtypes: weakly spiral, strongly spiral, strongly curly, slightly curly, curling. Cross section - flattened oval shape.

The structure of human hair is its main characteristic, on the basis of knowledge of which the development of products for the care and treatment of curls is carried out. When the structure of the hair is disturbed, problems appear, such as dullness, fragility, etc. Restoring this structure is the goal towards which all the actions of professional and folk remedies for hair.

Scalp

The scalp can cause hair problems. Thus, its excessive production of sebum leads to the fact that the strands quickly become dirty, stick together, and seem stale. Insufficient production, on the contrary, leaves the curls defenseless against exposure environment, because a protective film is not created on them.

The skin has three main layers:

1. Epidermis (external);
2. Dermis
3. Subcutaneous fat (lowest layer).

Skin tissue has this structure on any part of the body. Epidermal cells are dead, you remove them during combing and washing. This removal of skin scales is associated with the appearance of dandruff. The epidermis also consists of the shiny, basal, granular and stratum corneum.

Interesting fact: the cells of the basal layer of the epidermis are renewed twice - early in the morning and in the afternoon, until 15:00. It is during this period that any care will be most effective.

The dermis is the main layer of the skin. It contains nerve endings and blood vessels, capillaries. It contains collagen - the key to skin elasticity and youth. The dermis contains sebaceous glands, and hair follicles pass through it and the epidermis. The hypodermis or subcutaneous fatty tissue is “engaged” in thermoregulation of the body.

Composition of hair on the human head

The composition of human hair is not very complex. It cannot be called living tissue. However, it grows due to active cell division in the area of ​​its base. However, the shaft that is visible to us has no nerve endings, is not supplied with blood and, like nails, is a static “dead” formation.

The main component in the composition is keratin, that is, a protein formed by compounds of amino acids such as cystine and methionine. It also contains sulfur atoms. Protein (keratin) in healthy hair that has not been subjected to thermal, chemical treatment or dyeing contains about 80% or slightly less. About 15% water, 5 – 6% linides and 1% or less pigment.

But the composition of the hair can change. This occurs under the influence of several factors:

1. Taking certain medications;
2. Performing certain medical procedures and manipulations;
3. Coloring, lightening, tinting hair;
4. Frequent and intense heat treatments (blow-drying, straightening, curling, etc.);
5. Chemical treatments, both positive and negative (masks, balms, perm/straightening);
6. Bad habits (smoking, alcohol);
7. Eating disorders, diets;
8. Changes in metabolism.

Normal chemical composition of hair - important rule proper hair care. Only such strands are responsive to treatment and do not cause problems for their owner.

The secret of hair structure

Knowing the structure of hair is important for proper care. This will help you choose the right care products, comb and style your strands correctly, handle strands more carefully, etc.

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It was said above that at its base, hidden in the skin, each hair has a “living” zone from which growth occurs. In this zone, active cell division and generation of new hair occurs. The rate of cell division there is very high. The zone is located in the deep layers of the dermis, essentially on the border with the hypodermis, at the very bottom of the hair follicle.

This area is called a follicle. It should not be damaged, since it is the one that is most important during regrowth. The follicle is fed with blood from blood vessels, which can also be considered part of the hair. In addition, there are other parts:

• Root;
• Papilla of the hair follicle;
• The hair muscle (they are the ones responsible for the appearance of “goose bumps” when they contract);
• The sebaceous gland produces sebum and is responsible for protecting the hair and scalp.

All of these organs are located in the dermis. Only the rod itself passes through the epidermis. This is his visible part. The rod is partially located in the skin and its maximum part is outside it.

The follicle is an important part of the hairline

The structure of the follicle is complex. Essentially, this is the entire part of the hair that is responsible for its growth and is located under the skin. Synonym: hair follicle. Since this area is alive, a person experiences pain when removed “from the roots.” With such regular removal, the root is damaged and the hair stops growing at all.

The hair papilla is a large formation responsible for the growth and life of hair. When removed, if it survives, a new hair will soon grow. If the papilla has been damaged, it will not recover. It is penetrated by blood vessels and nourishes the hair with essential substances.

The piliary muscle attaches to the follicle just below the sebaceous gland. It contracts under the influence psychological factors and in the cold. As a result, “goose bumps” appear and “hair stands on end.” The sebaceous gland itself is not part of the hair. But it is necessary for its normal development.

Cuticle

Like nails, hair has a protective cuticle. It is located on the rod and is its outer layer. Quite a thick layer (comparable to the thickness of a hair). Consists of 5 – 10 layers of cells. They are keratinized, large, elongated and lamellar in nature. These are what are commonly called “hair scales.”

They are located similarly to tiles, so damage to even one such plate leads to unpleasant processes throughout the entire rod. They overlap each other in the direction from roots to ends, so the ends should be protected especially carefully.

Performs a protective function. It is on this that the smoothness, shine and appearance. Function of balms, masks, etc. means - closing the scales and thereby restoring maximum protection. While shampoo, on the contrary, opens them up for maximum cleansing.

Hair section under a microscope

Cortex is a strong core

The cortex is the main part of the rod. The thickness of a human hair depends on the volume of this part. The cortex makes up 85% of the entire hair. While the remaining 15% is shared by the medulla and cuticle. The cortex consists of pure keratin protein. In one short hair there can be tens of thousands of such keratin fibers.

Collagen fibers are sequentially intertwined, forming chains. These chains, intertwined with each other, form the hair shaft itself.

It is in this part that most chemical processes occur. Pigment coloring. Its color changes in the cortex. The pigment penetrates through the cuticle scales, opened by paint, to the hair's own pigment and changes it. Other chemical processes in this part of the hair operate similarly.

Medulla

The structure of the hair on the head has a medulla. This is the central part. It is located under the layers of cuticle and cortex. Not every type of hair on the human body has this part. Vellus hair and some other types on the body lack this part and only have a cortex and cuticle. This part has nothing to do with physical properties or structure. In fact, it is not needed. Responsible only for the thermal conductivity of the strands. Chemical processes it is also missing.
It consists of brain matter. Inside it there are microscopic air bubbles, which heat up (or cool down). Due to them, thermal conductivity, temperature change, etc. are achieved.

Medulla in the center of the hair

Growth phases with pattern

Growth occurs in three phases. Moreover, hair types and their structure do not in any way affect the presence of these phases or their duration. Throughout life, each hair cyclically and repeatedly goes through three stages:

• Anagen – growth. Lasts 2 - 6 years. How older man, the shorter this phase (i.e. growth slowdown). At this stage, cells divide rapidly;
• Catagen is a transition period to the third stage. On it, the papilla begins to gradually atrophy. Blood supply decreases and then disappears. There is no growth. The hair follicle is deprived of nutrition, the cells become keratinized. Catagen lasts 2 weeks;
• Telogen is a short stage. Hair does not grow or develop; it is a “resting” stage. At this stage they fall out. If a person has increased hair loss, this stage occurs too early. After the telogen hair is removed, a new one begins to grow and the anagen stage begins.

The structure of the hair does not change. Thus, during a person’s life, each follicle is capable of reproducing about 10 hairs.

Take care of your hair!

Hair is not only a person's decoration. They are used to identify personality, gender, and sometimes social status. Therefore, everyone strives to have strong and healthy strands. Knowing the structure of hair and scalp, nutrition and vital functions, you will be able to provide proper care for your curls and make them strong and beautiful.

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

• Epidermis
• Dermis
• Fat fiber

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. When they die, they peel off, but new ones immediately form in their place. This is how 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 layer of skin located in the middle and consisting of countless strong elastic fibers. There are muscles and blood vessels, sebaceous and sweat glands, as well as follicles and roots of strands. Thanks to this layer, the skin has 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 are nourished.

What is human hair made of?

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

Shaft 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 special feature of the rod is the ability to stretch 1/5 of its size without feeling pain.

The follicle, or hair follicle, is hidden inside the skin. It is “alive” and is responsible for the growth of strands. It is into it that the channels of the sebaceous glands exit, giving the curls radiance and elasticity. A slight release of this secretion leads to the fact that the curls look dull and lifeless. Conversely, the functioning of the sebaceous glands can be excessive, as a result of which the hair quickly takes on a greasy and dirty appearance.

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

Keratin, a protein made from amino acids, is the main “building material” 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 curls directly depends on how much these vitamins are sufficient for the human body.

The chemical composition of healthy hair is approximately the following:

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

The chemical composition of the strands may change, depending on whether the strands were exposed to chemical and physical influences, or if diseases are detected.

Structural features

Hair is a special skin formation characteristic of representatives of the mammalian world and humans. A significant part of the surface of the head is covered with this kind of thread-like formations.

Follicle structure

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

The follicle looks like a small depression containing a root, which is shaped like a sac. Downwards it is somewhat expanded, forming a hair follicle, to which blood vessels, sweat and sebaceous glands are supplied. They are responsible for feeding and removing waste products from the strands.

Nutrition of the hair follicle is possible thanks to the vessels approaching the papilla. It is located at the very base of the bulb. If the hair falls out, it is only along with the bulb itself.

Structure of the hair shaft

The diagram of the hair shaft clearly demonstrates all its features.

Looking at the structure of hair through a microscope, you can clearly see three main parts:

• Cuticle
• Cortex (cortical layer)
• Medulla (medulla)

1. The cuticle is the layer on the outside. It is based on keratinized scales, arranged like tiles, 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 curls from external influences. Each cell of this layer contains a fatty acid, which gives the strands a water-repellent effect. Also, thanks to it, the scales adhere closely to each other. Fatty acid cannot be removed by regular hair washing, but can be easily damaged by chemical treatments.
   The porous or glassy structure the hair will have is determined by the properties of the cuticle. Porous strands are dry, brittle, and quickly absorb dirt and chemical components. The glassy structure of curls is elastic and dense.
2. Directly below the cuticle is the cortical layer - the cortex. He is responsible for ensuring that the curls are elastic. The structure of this part determines whether the strands will be straight or curly. The fact that the cortex is well developed explains the ability of hair to curl or stretch. If the cortex is insufficient, the strands begin to break.
   It is the cortex that consists of 90% keratin. The remaining 10% comes from 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, when mixed with pigment, to give the hair a variety of shades.
3. In the very center is the medulla - the medulla. However, it may not be present in very fine hair. In animals, this layer provides thermoregulation. In humans, this function of the medulla is absent due to the voids contained in it.

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

The extent to which a person’s medulla is developed, the extent to which his hair will be voluminous and strong. This easily explains why it can be so difficult to grow thick hair without a genetic predisposition to it.

What functions does hair perform?

Main functions of hair:

• The protective function is that hair prevents ultraviolet radiation from penetrating the skin during exposure to direct sunlight.
• Thermoregulation. It’s hard to believe, but it was hair that protected a person from colds in those days when there were no warm clothes. When cooled, they rise, thanks to the erector muscles, and retain their own heat against 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 is especially noticeable when an insect crawls on your head.

Hair structure and growth

Within a month, the strands are able to increase their 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 reproduction occurs in the cortex. As it moves towards the surface layer of the scalp, the hair thickens, becomes keratinized and filled with hard keratin.

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

At the mouth of the hair follicle, the ducts of the sebaceous glands exit. The released oil substance reaches the surface of the skin of the scalp and lubricates the curls, making them smooth, elastic and radiant.

Everyone is capable of having healthy, beautiful curls. 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

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Function of hair in humans

Biological function of hair- protective. Hair on the head, prevent it from overheating and protect it in cold weather, as well as from mechanical stress (shock). Eyelashes protect the 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 eyes from sweat.

Hair structure

Approximate composition healthy hair:

• 78–90% squirrel(keratin)
• 6% lipids(fatty acids)
• 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 quantities: magnesium, arsenic, iron, phosphorus, chromium, copper, zinc, manganese, gold.

Hair consists of two enlarged parts:

• Kernel- the outer, visible part of the hair protruding above the surface of the skin.
• Root (follicle)- 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 is the shaft, mainly consists of a horny protein substance - creatine.

The hair shaft does not receive blood and has no nerve endings.. 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 transparent amorphous keratin cells, reminiscent of scales in structure (like those of a fish or a pine cone). The space between the scales is filled with lipid layers (fatty acids), thanks to which the scales fit tightly to each other. The scales are directed from the root of the hair to its tip.

  Function of cuticle Basically protective, which protects the cells of the inner layer of the hair shaft (cortex) from exposure to water, sun and mechanical stress.

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

  Basic function of the cortex- This is giving the hair shape, 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 is inherited genetically.

• medulla(central medulla) is the central part of the hair shaft, consisting of keratin-based 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. The medulla cells contain glycogen and may include melanosomes. The medulla is filled with air bubbles - due to this, the hair has a certain thermal conductivity. The medulla does not play any role in changing either the chemical or physical properties of the hair.

Hair root (hair follicle)

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

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

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

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

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

Hair begins to grow in the hair follicles.

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

Hair color

Among the cuticle scales, and among the cores of the cortex layer, Pigment granules are located in the form of melanosomes, which give the hair a certain color. Hair shade is determined by genetic factors and depends on the ratio of the content of 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 oil content of the hair itself.. Sebum spreads over the entire surface of the hair, covering it with a thin film. Depending on the “oily” content of the hair, it is divided into four types:

• oily hair(increased greasiness of hair)

• characterized by increased oily sheen
• stick together into separate strands
• elastic
• often thick

• quickly become dirty and lose their attractiveness
• cause difficulties when doing hairstyles
• are not electrified

• dry hair(reduced hair greasiness)

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

• normal hair(normal functioning of the sebaceous glands)

• moderate, healthy hair shine
• obedient when combed
• flexible and elastic
• no split ends
• are not electrified

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

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

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