At what stage of growth does hair stop growing? Structure, functions and phases of hair growth. Causes of premature loss

Hair growth stages:

In order to correctly carry out the procedure for removing unwanted hair, it is important to understand the nature of its growth and know that in two weeks or 1-2 months, not a single procedure will stop hair growth forever.

Hair goes through different stages of growth and, and elos hair removal affects hair that is in the active phase. Only about 30% of hair follicles in any area of ​​the skin are in this phase.

THEREFORE, to achieve , hair removal will have to be done at a certain frequency, which is not limited to 2-10 weeks.

Many people think that hair grows continuously, but only a small part of it falls out, and then very rarely. In fact, hair growth can be divided into 3 stages. Moreover, each hair cycles through all phases of growth many times throughout a person’s life.

Each hair grows differently, depending on age, body weight, metabolism, hormones, ethnicity, medications and other factors.

However, all hair goes through three hair growth cycles:

ANAGEN is a period of active hair growth. Lasts on average from 2 to 6 years. With age, the duration of the anagen phase decreases. The anagen growth phase is also divided into 6 stages:

1. The cells of the hair follicle increase in size, and intensive RNA synthesis occurs.
2. The hair bulb grows down into the epidermis and practically surrounds the dermal papilla. Cells begin to differentiate into different layers of hair and outer root sheath in the matrix ring that surrounds the dermal papilla.
3. Cell division continues. At this point, the hair follicle reaches its maximum length, which is 3 times longer than in the resting phase. The dermal papilla is also fully formed. Melanocytes (epidermal cells responsible for the production of melanin, which gives hair its color) are located along the cavity of the papilla, each of which (each of the melanocytes) forms melanin granules. The outer lining of the follicle cavity is now an elongated cone, expanding at the top.
4. At this stage, melanocytes begin to produce melanin (pigment). Although the hair has already been formed, it still does not extend beyond the boundaries of the cone-shaped cavity, which continues to expand.
5. The hair grows to the upper border of the epidermis, the bulb acquires a complete shape, which in some hairs is symmetrically round, in others it is compressed like an ellipse.
6. The last stage begins as soon as the hair begins to rise above the skin and continues until the catagen phase. This stage lasts 2 or more years. Hair reproduces at a rate of 0.5 mm per day.

CATAGEN - the period of transition from one stage to another. In the catagen stage, atrophy of the hair papilla begins, as a result of which the cells of the hair follicle, deprived of nutrition, stop dividing and undergo keratinization. This stage lasts only a few weeks, after which a short telogen stage occurs, which smoothly transitions into the developmental stage.

TELOGEN - period of rest or rest of the hair. Interestingly, mechanical removal of hair that is in the telogen stage always entails the onset of the anagen stage, that is, the hair begins to grow again. Any hair that remains on the brush or falls out during the day is telogen hair.

Typically, in healthy people, approximately 80-90% of hair is in the anagen stage, 1-2% in the catagen stage and 10-15% in the telogen stage. Research shows that heavy hair loss corresponds to a change in the above ratio: the percentage of anagen and catagen hair decreases, but the percentage of telogen hair increases.

If you notice that the amount of hair falling out during the day has increased sharply, then know that this is the first sign of deterioration in the condition of your hair. In people who are not prone to baldness, each new hair does not differ in thickness, potential length and other characteristics from the previous ones; at the same time, in those who are balding, each new generation of hair decreases in thickness, color (lightens), the growth rate and duration of the anagen phase decreases. Ultimately, healthy hair gradually degrades into vellus and colorless hair.

Distribution of body hair in men and women

A man with pronounced body hair

Hair removal, also known as "epilation" or "depilation" is the removal of body hair. The term applies to methods of achieving a given result.

Many products on the market turn out to be fake, exaggerating results or ease of use.

Kinds:

• depilation- removal of hair above the surface of the skin. The most common type of hair removal is shaving or haircut. Another option is to use chemical depilatories, which work by breaking the disulfide bonds that connect the protein chains that give hair its strength.

• epilation- This is the removal of the entire hair, including the part that is under the skin.

Hair growth phases

The process of hair growth is cyclical and continues throughout our lives. Hair grows continuously. It has been established that during the day they grow faster than at night, and in summer and winter their growth slows down. The average hair growth rate in children is 13 mm per month, in adults - 15 mm and in older people - 11 mm.

The complete development cycle of a fully formed hair consists of three phases: anagen, catagen and telogen.

Anagen- active growth phase. The duration of this phase is determined genetically and lasts from two to five years. At the same time, the cells of the hair follicle rapidly divide.

Catagen- The intermediate phase lasts several weeks. Hair growth in the follicle stops, pigment is no longer formed, the follicle shrinks, and its base moves towards the surface of the skin.

Telogen- rest or loss phase. During this phase, hair may fall out spontaneously or be removed with light force. The duration of the phase is on average 3 months. Hair falls out the moment new hair begins to grow underneath it.

According to studies, it is best to remove hair using the depilation method in the middle of the menstrual cycle in women, when hair growth is slowed down by 2 times.

Hair removal methods

Temporary hair removal at skin level (depilation) lasts from several hours to several days and can be achieved with:

• Shaving (manually or with an electric razor);
• Depilatories (creams or “shaving powders” that chemically dissolve hair);
• Friction (using rough surfaces).

Epilation, or hair removal from the roots, lasts from several days to several weeks, and can be done by:

Permanent hair removal (electrolysis)

Electrolysis has been popular in the United States for over 130 years. It is FDA approved. This method permanently destroys the germ cells responsible for hair growth by inserting a thin probe into the hair follicle and applying a current tailored to each hair type and area being treated. Electrolysis is recognized by the FDA as the only permanent hair removal method.

Permanent hair reduction (laser and other light types of hair removal)

• (laser diodes and lasers);
• (high energy lamps or IPL) or more commonly the method is called ;
• (IPL/any laser)
• Diode hair removal (high energy LEDs, not laser diodes)

Experimental or ineffective methods

Methods with unproven effectiveness

Many methods have been proposed or marketed without published clinical evidence.

• Electric tweezers
• Transdermal electrolysis
• Percutaneous hair removal
• Photoepilation
• Microwave hair removal;
• Nutritional supplements;
• Over-the-counter topical medications (also called “hair retardants,” “hair inhibitors,” or “hair growth inhibitors”).

Efficiency comparison

In a 2006 review article published in the journal Lasers in Medical Science, researchers compared intense pulsed light (IPL), alexandrite, and diode lasers. The review found no statistical difference in effectiveness but a higher incidence of side effects with the diode laser. Hair reduction after 6 months was 68.75 for alexandrite laser, 71.71 for diode lasers, and 66.96 for IPL. Side effects were reported at 9.5 for alexandrite laser, 28.9 for diode laser, and 15.3 for IPL. All side effects were temporary, even skin pigmentation was eliminated within 6 months.

Advantages and disadvantages

There are several disadvantages to many of the above hair removal methods. The main ones are: skin inflammation, burns, rashes, scars, ingrown hairs, and infected hair follicles. One issue that can be considered both a disadvantage and an advantage depending on the person's point of view is that hair removal has the effect of removing information about a person's hair growth pattern due to genetic predisposition, disease, androgen levels (e.g. for hormonal imbalances during puberty or side effects of medications), and/or gender status.

Another disadvantage of permanent (laser, electrolysis) hair removal is the reduction in the ability of human skin to regenerate, since hair follicles contain stem cells that help healing.

Cultural and gender aspects

Hair is usually present throughout the human body; during puberty, the hair thickens and changes color to a darker color. Generally, men have more visible body hair than women. Both men and women have visible hair on the scalp, eyebrows, eyelashes, armpits, pubic area, arms and legs; men also have thicker hair on the face, stomach, back and chest. Hair usually does not grow on the lips, the inside of an arm or leg, or in certain areas of the genitals.

Each culture of human society has its own social norms regarding the presence or absence of body hair, which have changed from one generation to another.

The practice of hair removal in almost all cultures dates back to Paleolithic times. Methods and locations of removal have varied across time and culture, but shaving remains the most popular method. Different standards have occurred in both women's and men's fashion. People who did not adhere to the aesthetic norms of society faced real or imaginary problems in society. In the Middle East, removing hair from a woman's body has been considered good hygiene based on local customs for many centuries.

With the increasing popularity of revealing clothing (swimsuits, tops, shorts, etc.), the popularity of body hair removal has also increased (legs, armpits, etc.). In the US, the vast majority of women regularly shave their legs and armpits, while about half also shave their bikini line.

Most people remove pubic hair for aesthetic or sexual reasons. However, some Western women, as a matter of principle, do not shave their hair from open areas in order to protest against society’s imposed patterns and aesthetic rules.

Men are forced to shave their faces every day also for the sake of aesthetic norms and rules. However, some men shave their beards because their beard color is different from their scalp hair color, or because their facial hair grows in different directions, making it difficult to look well-groomed.

The phases of hair growth include active, intermediate and final stages.

Hair can be renewed several times throughout life.

The cyclical nature of hair growth is often compared to the process of plant development throughout the year: roots form in the spring, active growth occurs in the summer, fueled by beneficial substances from the earth, and in the fall a period of fading and gradual death begins.

Hair has two parts: living and dead. The first is located under the epidermis and is responsible for growth and structure, the second is the outer covering on the head, the appearance of which people care so carefully about.

Visually attractive hair with good shine is often called “living.” However, the outer part, called the shaft, consists mainly of dead cells.

It has three layers:

• cuticle, which performs a protective function and is important for appearance;
• cortex, responsible for strength, elasticity and color;
• medulla - the central trunk through which beneficial substances supposedly flow to the outer layers.

The appearance of the curls on the head largely depends on the condition of the cuticle, which includes many keratin scales.

In a normal state, they fit tightly to each other, but when damaged, they separate, forming voids.

Such processes begin if the hair is subjected to intense physical and chemical effects.

In this case, the hair loses its shine and elasticity, becomes brittle and unattractive.

The appearance of the strands is primarily influenced by the condition of the bulb (root), located under the epidermis and surrounded by the follicle.

An interesting fact is that the shape of the hair follicle determines the type of hair: curly grows from a kidney-shaped follicle, straight from a round one, and curly from an oval one.

The hair follicle and the surrounding pouch are located in the dermis and are fed from the subcutaneous fat base and the circulatory system through the papilla (papilla).

Also under the epidermis, adjacent to the follicle, is the sebaceous gland, which is responsible for fat lubrication and antiseptic protection.

The intensity of functioning of the cells of the papilla and follicle determines the stages of hair growth.

Three main growth phases

About 85% of the hair on your head is in a growth stage called anagen. The duration of this phase can be several years - from two to five.

On average, hair grows by 12-15 mm within a month. The intensity of growth depends on the time of day and season; it is more active at night, in spring and autumn.

The hair follicle is formed in the dermis and is fed with nutrients through the nipple. In the anagen phase, cell division processes are as intense as possible.

The root thickens and stimulates the growth of epidermal derivatives - rods. As life progresses, the root moves closer to the epidermis, moving away from the nipple, the source of nutrition.

The papilla functions throughout the active phase, however, the distance of the bulb from the papilla contributes to the disruption of normal metabolic processes.

During this period, growth slows down and gradually stops altogether. This stage is called catagen or the intermediate phase before the shedding stage and lasts up to three weeks.

The follicle shrinks and stops performing its functions. The nipple also gradually slows down vital activity.

The third and final stage is called the telogen or resting phase. During this period, hair does not grow, but continues to remain on the head.

The hair follicle is no longer fed from the follicle and gradually atrophies. The rods lose their elasticity and fade away.

This stage can last up to three months, then natural loss occurs.

It has been established that every day a person loses about 100 hair shafts, which mainly include hair in the telogen phase.

Such losses are not critical, since the number of rods on the cranial vault can reach 150 thousand.

If the loss is more intense and the process progresses, then this indicates disturbances in the body or the presence of a disease - alopecia.

The problem of hair loss is quite common, so cosmetics that counteract this phenomenon are in high demand among consumers.

In most cases, loss is a natural physiological process.

After a certain period of time, the nipple resumes its activity and promotes the formation of a new hair follicle from the mother cells.

The developing root pushes out the keratinized parts of the predecessor.

Removal of rods from atrophied bulbs can also occur during combing or other physical impact on the hair.

The intensity of hair growth changes throughout life; this process is most active at the age of 16-24 years.

In older people, hair becomes thinner and grows more slowly - up to 11 mm within a month.

Causes of premature loss

The structure and appearance of hair depend on the processes occurring in the subcutaneous part: inside the bulb, follicle and nipple.

With a deficiency of nutrients, the root may prematurely atrophy, and the rod may lose elasticity and shine.

Special cosmetics help normalize these processes in case of imbalance or other disorders.

For example, hair can become dry if the secretion secreted by the sebaceous gland is not supplied in sufficient quantities, and, conversely, oily if increased secretion occurs.

Incorrect coloring can destroy the hair follicle under the influence of deeply penetrating chemical elements, which will lead to a premature transition to the catagen stage.

Loss or growth retardation is mainly caused by dysfunction of the follicle and nipple. Timely therapy contributes to their recovery.

Therapeutic agents are aimed at shortening the resting phase and stimulating follicular activity. Weakening and thinning are also signs of root failure.

Therefore, all treatment methods are aimed at strengthening the hair follicle and restoring the functioning of the nipple.

Hair care involves, first of all, caring for the roots - the sources of life of the hair.

Hair grows on all human skin, with the exception of the palms and soles. On our body there are areas with dense vegetation, as well as barely noticeable, almost transparent hairs. Initially, their role was protection. But in the process of evolution, the functions changed and became an attribute of decorative rather than necessity.

To effectively perform various hairdressing procedures, such as coloring, bleaching, perm or straightening, you need to know what the hair is made of, what elements are involved in the reaction when applying dye, caring or shape-changing substances. Let's learn about the structure of human hair, how and from what its bulb, follicle, shape and color are formed.

Changes in hair structure throughout a person's life

During observations by scientists of the process of human hair growth, it was found that its formation occurs even before birth, and at different stages of life its structure changes. How does this happen?

1. The cannon ones appear first. They grow at birth and remain with the child until the age of three. The name itself says that their structure is very soft and thin.
2. Between the ages of three and sixteen years, a child begins to develop teenage hair, which develops into a genetically determined type and it is already possible to determine what it will be like in the future.
3. During adolescence - 16–17 years, the hair enters the maturity stage. And by the age of 18, the formation of their structure is finally completed.

During puberty, men begin to develop hair on their body and face - a mustache and beard. And for women - only on the body. In old age, older people experience intensive growth of eyebrows, hair appears in the ears and the amount of hair in the nose increases. With age, the structure becomes tougher, and the bulb goes deeper into the skin.

Growth begins due to active cell division in the outer layer of skin. This growth is called a “hair bud,” which then takes on a teardrop shape and subsequently becomes a follicle. As the droplet (tongue) moves deeper into the skin, the cell continues to divide. This expanded accumulation of cells turns into a hair papilla, which is overgrown with protein and a head with a pointed tip is obtained - a bulb. Thus, the protein in the hair is formed even before it appears on the surface of the skin. The structure of the follicle, and then the bulb, involves cells - melanocytes, in which the future pigment is laid, as well as a protein - keratin, consisting of amino acids.

Nutrition of the root and the influx of building substances is carried out through the papilla connected to the blood vessel, from which hair growth begins. The follicle becomes horny and through the hole formed in its core, a small process appears, which, breaking through the layer of skin, comes out.

The new (primary) hair is called papillary hair because it is fed directly from the blood vessel. Gradually, the supply of keratin from the papilla stops, the hair grows into the canal more strongly, its growth stops and loses connection with the nourishing organ, and the bulb becomes horny. In this condition, the hair is called flask-shaped. They remain in the skin for a long time, so most of human vegetation consists of them.

Then, the cellular mass located under the flask-shaped hair begins to divide again and forms new tissue, which pushes out the old one. Young hair that grows in place of the lost hair is called secondary hair. This is a continuous natural process. The daily rate of hair loss is 60–100 hairs. Their maximum lifespan is 6 years.

Hair growth phases

Since replacing old hair with new ones is a constant process, it has a certain cycle, which consists of several phases:

• anagen;
• catagen;
• telogen;
• early anagen.

What do they mean?

1. Anagen is the phase of active cell division in the hair follicle. During the growth of the bulb, the synthesis of ribonucleic acid begins in the skin around it. In this phase, the hair papilla receives the most intense nutrition from the blood vessels. At the same time, the bulb connects with the nerve endings - which is why pain occurs when a hair is pulled out from the root. In the anagen phase, pigment is also laid. This stage of growth completely forms the bulb and future hair, the life of which will last from two to six years.
2. Catagen is an intermediate phase that occurs after active growth. During this period, the supply of nutrients to the papilla and the synthesis of melanocytes stop. Hair growth stops and follicles become keratinized. The intermediate stage lasts 2–3 weeks.
3. Telogen is the resting phase when the bulb becomes completely inactive. The nutrition ends and the papilla goes into a resting state, but the hair flask remains on the surface for another 2–3 months, and then painlessly leaves its pouch. About a hundred telogen hairs fall out every day. The total duration of this phase can be up to six months.
4. Early anagen is a period of active formation of secondary hair under the old bulb that has not yet fallen out.

This process is continuous, but with age it slows down and the anagen phase shortens. Over time, some follicles lose the ability to form new hair. And in some cases, most of them die off completely and alopecia sets in - partial and then complete baldness.

Hair shape

What the hair will be like - straight, wavy or very curly - depends on the shape of the canal in which the bulb originates.

1. Smooth hair is formed from a straight channel.
2. Wavy - from crescent-shaped. The more the channel is bent, the greater the curliness.
3. Tight negroid curls grow from spiral channels.

Thus, the future shape of the hair is laid before it appears on the surface of the skin.

If you look at different types of hair in cross section under a microscope, you will notice the following differences.

1. Asian ones are most often thick, straight and rigid, and their cross-section is round.
2. European ones are usually of medium thickness, slightly wavy, and the cross-section is elliptical.
3. Negroid - hard, curly, ribbon-shaped in cross-section.

The shape of the channel affects not only what the hair will be, but also its cross-section.

Hair structure

When examining a section of human hair through a microscope, you can see that it consists of three main layers:

• scales - cuticles;
• cortex - cortex;
• and the core - the rod, medulla or medula.

It also has a cylindrical shape.

Let's take a closer look at the structure of all layers.

1. The hair cuticle (scales) is a protective layer from outside influences. It consists of horny leaves arranged in a checkerboard pattern, which look like a fir cone or fish scales. These petals are sensitive to alkaline or acidic influences.
2. The cortex has a complex structure. It is formed from elongated fibers intertwined with each other. This layer contains pigment, hydrogen and sulfur bonds, and nutrients.
3. The structure of the rod (medula) is formed from the brain cells that form the basis of the flask. The remaining layers are attached to this core.

In addition, the fatty gland and muscle also participate in the formation of hair.

1. The fatty gland is responsible for elasticity and preventing keratinization of the hair and scalp. And also the production of sebaceous secretion - a natural fatty film, protects against the penetration of surface contaminants.
2. The muscle presses the hair to the scalp, creating protection from the cold, or in case of nervous shock. The figurative expression “the hair stood on end” becomes real thanks to this particular muscle.

Each component in the hair structure is responsible for a separate function.

The structure of human hair

Chemical composition

Man is entirely composed of elements from Mendeleev's periodic table. You need to know the chemical composition of hair in order to predict the reaction of various drugs when performing long-term styling and coloring procedures.

The ratio of chemical elements in hair is as follows:

• carbon (C) - 49.6%;
• oxygen (O) - 23.2%;
• nitrogen (N) - 16.8%;
• hydrogen (H) - 6.4%;
• sulfur (S) - 4%.

They influence the quality of coloring, the durability of the pigment, as well as the formation or straightening of the curl.

The substances that make up hair form fibrillar protein - keratin and all its amino acids. This is the main building material.

Keratin consists of the following amino acids:

• alanine;
• arginine;
• aspartic acid;
• valine;
• glycine;
• histidine;
• glutamic acid;
• isoleucine;
• leucine;
• lysine;
• methionine;
• proline;
• serine;
• tyrosine;
• threonine;
• tryptophan;
• phenylalanine;
• cystine.

The lack of at least one amino acid in human hair leads to its fragility, and the hair follicles to irreversible death and loss. Keratin has high mechanical strength, second only to chitin, which forms the keratinized parts of animals.

Types of connections

When the color changes as a result of dyeing, or the shape of the hair when curled or straightened, its hydrogen or sulfur bond changes. What is it and what effect do chemicals have on it?

1. Hydrogen (longitudinal) bonds are single bridges located along the hair. They are responsible for changing natural or cosmetic pigment. The reaction of the dyes is based on the interaction of hydrogen oxide with the fibrous substance of the cortex.
2. Sulfur (cross) bonds are double bridges located across the hair. They are less fragile than hydrogen ones. They are responsible for the shape - the stronger the disulfide (double sulfur) bond, the more intense the curl. The main reaction of drugs for long-term styling lies in the effect of sulfur-containing compounds with these bridges in the cortex.

All modern chemical products are synthesized from components most similar in composition to human hair, so that they are embedded in its fibers and do not break the bonds, but delicately stretch them.

Pigment

This is the color that the human eye sees. It is laid before birth and depends on genetic characteristics. Color is formed in the cortex from melanocyte cells, which represent two types of natural pigments:

• melanin - black or brown;
• pheomelanin - red or yellow.

A natural base is formed by combining these types of pigments. This is the color that is given to a person at birth.

But pigments can also be cosmetic - this is a color acquired through dyeing. When creating a cosmetic base, dye molecules push out the natural pigment and integrate into the resulting voids.

Let us summarize by recalling the main points. Hair covers almost the entire body, with the exception of the feet and palms. Their structure and structure depend on the period of a person’s life. In newborn children they are vellus, and after three years they turn into teenagers. Final formation is completed at puberty. Hair formation occurs even before the baby is born. Its color and shape depend on the genetic disposition of the person. Before the hair tip appears on the surface, complex biochemical processes of cell division take place inside the skin, forming a papilla connected to a blood vessel, and then overgrown with nerve endings. Hair growth and loss is a natural and continuous process. The cycle consists of three main phases - anagen, catagen, telogen, as well as one additional phase - early anagen. The daily rate of hair loss for an adult is 60–100 pieces. Thus, the growth of new hair does not stop until the end of life.

Hair structure - cuticle

Hair structure - cortex and medula

Hair reflects the state of health of the human body. Diseases of the hair and scalp, changes in the amount of hair, its color or structure indicate living conditions, metabolic levels, hormonal levels and emotional stability of a person.

What is hair made of?

Hair is an elongated, modified upper layer of the skin (epidermis). The hair follicle (sometimes called “bag”) is also formed from skin epithelial cells.

The structure of the hair, regardless of where it grows, has the same structure and consists of three anatomical formations:

• root
• rod
• tops

How roots work

The hair root is located in the hair follicle. Its lower part contains nerve endings and small blood vessels (capillaries). Nerve endings transmit signals to the brain about the condition of the hair and changes in the external environment, and the vessels supply the bulbs with blood. For example, when there is not enough oxygen in the hair follicle, the nervous system reacts to this condition and dilates the vessels that are “supplied” to each hair.

Small muscles also approach the roots of the hair. They regulate the position of the hair and compress the blood vessels. Due to these muscles, during hypothermia and overheating, as well as in a state of acute stress, a person develops “goose bumps”. If the small vessels entwining the hair follicles are constantly compressed, then the hair suffers from a lack of oxygen - the follicles die irrevocably (atrophy).

Also, the sebaceous glands open into the hair follicles. They provide the hair with the necessary lubrication to protect it from heat or cold, as well as from dehydration. The “fatness” of the hair is the same as that of the areas of the skin where the hair grows.

Since the armpits have an increased number of sebaceous glands, the hair color in these areas takes on a reddish tint, no matter what color the hair on a person’s head is.

How does the hair shaft work?

The hair shaft is located above the surface of the skin and throughout its entire length consists of three layers:

• external (cuticle)
• middle (cortex)
• central - core (medulla)

The outer layer in the form of a dense shell consists of scaly cells folded like tiles. The cortex contains melanin, the pigment that determines the natural color of hair. The medulla - the core of the hair - contains cells with keratin (from the Greek "keratos", which means "horn"). The hardness of the hair depends on its quantity.

Tops (tips) of hair

The apex ends with the hair shaft. It has a pointed shape because it is the tip of the young hair that first grows out from under the skin. The ends of the hair have less melanin because they consist mainly of outer layer cells. There are significantly fewer cortical cells in them than in the rod, and the medulla is completely absent.

Types of hair

Hair follicles are found on all areas of the skin. The exceptions are areas with thick skin:

• palms
• soles
• dorsal surfaces of nail phalanges

On different parts of the body, hair is divided into the following groups:

• cannon- located everywhere
• long- grow on the head, beard and mustache,
  in the armpits and pubic area
• bristly- on eyebrows, eyelashes, nostrils

Hair groups differ in the content of the horny substance - keratin. The more it is, the tougher the hair structure.

How hair grows

Hair is formed from the germ layer - ectoderm. It is the hardest and most durable organic material. It also produces tooth enamel. Hair begins to grow already at the stage of intrauterine development of its owner.

Hair in people of different ages

From 15 weeks During intrauterine life, the fetal body is already covered with vellus hairs.

From 20th week vellus hair on the head, eyebrows and eyelashes of the fetus becomes stiffer. Melanin begins to flow into the hair follicles, which determines the color of the hair.

By the end of the first year Throughout a person's life, the hair structure is completely formed.

By the end of the third year vellus hair on the head is completely replaced by long hair.

By the age of five baby keratin fills the space of the hair cortex, and the final hair color is established.

During puberty In a person's armpits and pubic area, vellus hair is also replaced by long hair. During adolescence, boys' hair can become very dark. This is due to the increased production of male hormones - androgens. Hormones affect the muscles of the hair follicles. There is a mechanical “squeezing” of melanin into the hair shaft.

Hair growth doesn't stop throughout life. Horror stories tell of hair and nails growing even after death. In fact, post-mortem hair lengthening is associated with drying out of the skin. The skin becomes thinner by 2-4 millimeters. Accordingly, the hair lengthens by the same amount.

During life, regardless of acquired gray hair, hair development occurs cyclically. One growth phase follows another. Upon completion of all phases, the hair growth cycle begins again.

At the age of one, it is customary for many nations to cut girls and boys' hair to zero. This folk tradition speeds up the replacement of vellus hair with “permanent” hair by two years.

Hair development cycles

The life cycle of hair consists of three stages:

1. Growth stage. Anagen phase (from the prefix "ana-" (gr.) - rise and the words "genesis" (gr.) - birth).
2. Maturation stage. Catagen phase (from “kata-” (gr.) - descent, completion).
3. Rest stage. Telogen phase (from the Russian word “body-” and the word “genesis” (gr.) - birth, in this case means “becoming”).

The hair growth phase lasts for 2-5 years. First, keratin is produced, then cells of the coloring pigment, melanin, migrate into the hair cortex.

During the intermediate phase of development, the grown hair cells mature. Inside the bulb, a vellus rudiment is already forming to replace the mature hair. The duration of the hair maturation stage is 5 weeks - just like in the prenatal period, the same amount of time passes from the moment a person develops vellus hair until it begins to be replaced with coarse hair.

In the final (resting) phase, the hair does not grow, but is in the stage of full maturity. The stage lasts for 10-11 years. At the end of its life cycle, the hair falls out and is immediately replaced by a new one. Each hair follicle has the potential of up to 25-30 buds.

Duration of hair development phases:

The number of hair changes over a person’s entire life is easy to calculate: 2-5 years + 5 weeks + 10-11 years. This means that hair replacement occurs every 12-16 years.

External and internal factors reduce the innate strength of hair, and therefore its lifespan.

Causes of hair diseases

Like other organs of the human body, hair can hurt. There are both diseases of the hair itself and diseases of the scalp that have a bad effect on the condition of the hair. Because of this, the images in the photo and the names of these diseases sometimes coincide. Diseases of both the scalp and hair are caused by the influence of various harmful conditions (factors) on these organs.

The following reasons can lead to diseases of the hair and scalp:

• Radiation - hair can become thinner and break, thin out, and fall out.
• Unusual climate - high or low humidity and air temperature can lead to hair loss and deterioration of its structure (hair becomes porous, brittle, and falls out more actively).
• Toxins - for example, chemotherapy acts on the hair follicles from the inside, ending the resting stage of the hair before a new bud begins to form.
• Poor nutrition.
• Heredity.
• Hormonal disorders.
• Sudden severe stress.
• Infections.
• Oncological diseases.

Factors that can damage hair also include cosmetic “experiments.” Bleaching and repeated dyeing, blow-drying, and neglect of hygiene lead to excision of the ends, deterioration of the structure and increased hair loss.

For example, plucking eyebrows disrupts the elasticity of the forehead skin: premature wrinkles appear, the upper eyelid droops (ptosis). The consequences of hair removal are still being studied.

Hair diseases

Due to the reasons mentioned above, human hair can experience various painful conditions. If the body's functioning is disrupted, a person may experience excessive hair growth, complete or partial hair loss, deterioration in hair quality, graying, and scalp diseases.

Excessive hair growth

Conditions of excess hair growth include hypertrichosis and hirsutism.

Hypertrichosis is a hereditary condition in which there is increased hair growth, including on the head.

Hirsutism- this is the hair growth of women according to the male type (lower legs, mustache, beard). Hirsutism occurs due to an acquired or congenital disorder in the synthesis of sex hormones of the adrenal glands, as well as due to polycystic ovary syndrome. There are cases of male pattern hair growth in women due to uncontrolled (without a doctor's prescription) use of hormonal drugs.

Baldness

Baldness (alopecia) can be diffuse (over the entire head) or focal (in certain areas of the head).

Diffuse alopecia occurs more often in men. This is due to the function of male sex hormones - androgens. But not only androgens lead to hair loss on the head.

Baldness can begin in a state of chronic stress, in which the blood supply to the hair follicles is sharply reduced (as blood is redistributed in favor of vital organs: the brain, lungs and heart). In conditions of lack of oxygen, androgens encourage hair follicles to multiply at an increased rate. Thus, the required 30-35 cycles of hair development are reduced tenfold. The hair's potential is exhausted, the hair follicles close.

Alopecia areata - baldness of the scalp in certain areas of the head - is caused by a disruption in the functioning of the nerves supplied to the hair follicles. Alopecia areata occurs from infections that affect the nervous system, including syphilis. Infectious lesions of the scalp, leading to hair loss in limited areas, are also characteristic of ringworm and seborrhea. Also, focal baldness can be caused by a lack of vitamins in children or pregnant women.

Rapid graying

Hair diseases do not always and do not cause baldness or structural damage in everyone. Hair can also turn gray in just a few hours. This does not happen because the pigment disappears or evaporates from the hair; on the contrary, the saturation of the hair with melanin remains the same. The trick is that air bubbles trapped in the core of the hair distort its color. Oxygen enters the hair not from the air, but from the hair follicles: in their cells, during acute oxygen starvation, free oxygen is formed, the atoms of which migrate along the hair core.

Age-related graying occurs according to the same mechanism, but occurs more slowly. The cells of the hair follicle “age” and release oxygen molecules in small portions. The vascular branch on the chin, neck and jaw is less common than on the head. That's why the beard turns gray earlier. Graying of eyebrows is directly related to the amount of androgens. The fewer male hormones there are, the earlier eyebrows turn grey.

Thinning and brittle hair

Occurs due to a lack of vitamins, poor nutrition and oxygen supply to the bulb, and so on. At the same time, such and such disturbances occur in the hair, due to which it becomes thinner, breaks, splits, and becomes porous. A small subsection is missing.

Treatment of affected hair

Since hair reacts to damage within the body, when treating it, first of all, it is necessary to find and eliminate the cause due to which, in addition to other organs, hair suffers.

If a person suffers from cancer, then it is necessary to devote every effort to fight this disease. Then, if the treatment results are successful, the health of your hair will gradually be restored. For example, with alopecia, which is caused by treatment of a tumor, hair follicles are restored 1-2 years after the end of therapy.

If the cause of hair disease is hormonal imbalance, you need to restore the balance of hormones in the body.

In case of hair loss due to intoxication, it is necessary to rid the body of the harmful effects of poisons, after which vitamin complexes and additional local hair strengthening are recommended.

For rickets, vitamin D preparations are used to treat hair and the whole body. After the underlying disease is cured, hair growth is restored.

Infectious hair lesions are treated with antibiotics and antifungal drugs.

Not all hair conditions are curable. For example, treatment of baldness in men will be useless if hair loss is caused by age-related or natural hormonal changes - alas, when the hair follicles die irrevocably, there is simply nothing to restore in a specific area of ​​the skin. Also, graying due to stress or age is an irreversible process that is not affected by medications.

To strengthen hair roots, products containing B vitamins are used:

• B 1 (thiamine)— enhances neuromuscular transmission in the root zone of the hair;
• B 2 (riboflavin)– improves nutrition of hair follicles,
• B 6 (pyridoxine)- increases blood flow to the hair roots;
• B 9 (folic acid)– strengthens the cells of the epidermis of the skin, therefore, the hair shaft;
• B 12 (cyanocobalamin)- relieves oxygen starvation of hair follicles.

Natural vegetable oils, herbal infusions and natural clays (white, blue, green) are considered effective means for strengthening hair and treating dandruff at home. For example, burdock oil, when rubbed into the scalp, directly affects the hair follicles: improves their blood flow, nervous and muscle function, increases the elasticity of the hair and strengthens its fiber.

Infusions of burdock root, hops, nettle, and celandine have also long been considered excellent options for treating dandruff with folk remedies.