Where are the hair roots. The structure of human hair: known and not so facts and information

Hair is an important component of a person's appearance. We are proud of them when they are beautiful and thick, we are upset if they split or fall out, we make a huge number of hairstyles out of them, trying to make our appearance as attractive as possible. But what do we know about them? How do they work, what do they eat, how do they live and grow? But the hair structure is a complex system with its own special structure, life cycle and needs. Have you ever thought that if we knew more about our hair, perhaps we would be more careful and attentive to them, and they would always delight us with the shine of thick hair?

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What are

Hair is one of the protective elements of the body. Hair growth is observed, mainly in mammals. They have a visible part, it is called the stem, and the part hidden inside the skin is the hair follicle (it is also called the root in another way). The bulb is in a kind of "bag" called a follicle.

Did you know that it directly depends on the shape of the follicle, what type of strands decorates a person's head? From a follicle of a round shape, even strands grow, from an oval one - wavy, and from a kidney-shaped one - curly.

Each follicle has its own life cycle. It is a completely autonomous system that gives hair development and growth.

Hair is able to absorb moisture and is a conductor of electricity

The figure clearly shows the structure of the scalp, and the location of the hair follicle, blood vessels, sebaceous and sweat glands, etc.

Did you know that at birth, a child already has a certain number of follicles? How many of them will get from birth to a person - nature itself decides. It is impossible to increase their number during life.

The scalp has the same structure as the skin on the entire human body. She has three main layers: epidermis, dermis and fatty layer.

Epidermis- it is a protective, constantly renewing layer of the skin. Its outer cells are keratinized scales, the surface layer of which is constantly peeled off, and a new one takes its place. This process takes place throughout a person's life.

Dermis- This is the middle layer of the skin. It contains blood vessels, glands, muscles, hair follicles and hair roots. The sebaceous glands are connected to the hair follicles by channels. It depends on the work of these glands whether dry or oily strands will be on a person's head. The degree of skin elasticity depends on the condition of the dermis.

Adipose tissue also permeated with capillaries. It contains the lower part of the follicle.

Each hair follicle on a person's head has its own musculature. Thanks to her, the hair can move very slowly and almost imperceptibly.

What does the head of hair consist of?

In percentage terms, a person's hair has the following composition:

• 78% of the structure of our strands is keratin;
• 15% water;
• 6% fat;
• 1% - pigment.

The part of the hair located on the surface of the skin is the shaft. In the strands that cover the head of an adult, it consists of three layers:

1. Core- inner part. Has a scientific name - medulla. Medulla consists of soft non-keratinized cells. This layer is absent in vellus hair.
2. Cortical layer... The scientific name is cortex. In percentage terms, it occupies about 80 - 90% of the entire thickness of the rod. The layer consists of thousands of keratin fibers intertwined like a rope or electric cable.
3. The stratum corneum - cuticle- is formed from 5 - 9 layers of keratinized cells. Its appearance at high magnification resembles a bump or shingles, since it consists of a dense layer of scales overlapping each other. The appearance of the hair depends on the condition of the cuticle. If the scales are not damaged and fit tightly to each other, then the strands look shiny and silky.

If negative external factors begin to act on the hair, then first the cuticle is destroyed, and then the cortical layer. The structure of the rod becomes porous, the hair grows dull, loses moisture, breaks.

A good example of this effect is the discoloration of the strands. During this procedure, almost all the pigment is washed out of the rod, voids remain in its place, and the curls become more vulnerable and fragile.

The layers of the skin contain a very important part of the hair - the root. He is a kind of matrix, enabling growth... During growth, the cells of the bulb are in the process of continuous division. Active growth occurs due to the hair papilla. This formation is permeated by blood vessels, as well as nerve fibers. The growth and condition of the strands themselves depend on how healthy and active he is.

The hair root contains melanocyte cells. They are responsible for the production of pigment - melanin, defining color hair. There are two types of melanin in humans: eumelanin (shades of black and brown) and pheomelanin (shades of yellow and red).

In addition to melanin, hair color is affected by the presence of air bubbles in the core and middle, cortical layer.

The more bubbles are present, the lighter the shade and weightlessness of the hair. Most of the bubbles are found in gray hair. This explains their relative lightness and dryness.

How curls grow

Individual color, number of follicles, structural features and growth rate of human strands are due to genetic factors... It is almost impossible to radically influence their structure.

That is why you should not blindly rely on advertising of cosmetic products that promise to miraculously transform weak thin strands into chic hair. The most that hair products can provide is enhanced nutrition hair follicle, and as a result, get healthier and stronger curls. But no procedures will make the number of hairs on your head more than it is laid down by nature.

Strand growth is an ongoing process, but it is slightly faster during the day than at night. Also, the curls lengthen more intensively in spring and autumn, and in winter and summer their growth slows down a little.

Hair growth is a cyclical process that continues throughout a person's life. The life stages of a hair are divided into three cycles:

• anagen (active growth phase);
• catagen (intermediate period);
• telogen (phase of rest and loss).

Therefore, hair loss throughout a person's life is a normal process. In a healthy person, it passes almost imperceptibly, since about 85% of all hair is in the anagen stage, 14% in the intermediate phase, and only 1% in the telogen stage.

On average, the increase in the length of the strands per month is: for children - 13 mm, for young and middle-aged people - 15 mm, and for the elderly - 11 mm.

You can learn more about what hair is from the video.

Each person, like his hair, is unique. Therefore, there is no need to try to remake what is laid down by nature itself. From delicate soft strands, you will never make thick and hard hair. Better take care of proper care and nutrition of your hair, and you will see that it is actually beautiful, regardless of its type and density.

All people want healthy hair, but not everyone succeeds. This often happens because most people know little about the structure of hair, this truly amazing part of the body.

It must be said right away that every person has the smallest hairs all over their body. They do not grow only on the palms, nails, feet, lips and sides of the fingers. Body hair growth is a strictly individual constitutional feature. In some areas of the body, the hairline is barely distinguishable, in others they are of only one color.

Functions

Before talking about the structure of human hair, one should touch on such a topic as the structure of the scalp. In general, the skin covers the entire human body, its mass is 5% of the total body mass. The skin is made up of several layers:

• epidermis - the upper layer, consisting of partially dead cells, which are washed off during water procedures;
• basal;
• granular;
• shiny;
• horny.

The scalp performs a number of very important functions, without which the vital activity of the whole organism would be impossible. These include a protective function that prevents harmful microbes or other microorganisms from entering the body. It is the layer of the epidermis that prevents all kinds of mechanical damage. The immune function is designed to seek out foreign bodies and deliver them to the places of neutralization - the lymph nodes. With the help of the receptor function of the skin, a person has the ability to distinguish between tactile and temperature fluctuations and stimuli. Due to the metabolic function, the skin has the ability to breathe, as well as to produce secretions that create a thin film on its surface.

The thermoregulatory function contributes to the fact that when the temperature rises, the vessels expand, and when the degrees decrease, the blood flow slows down, respectively, the evaporation processes decrease.

The structure of the scalp and hair is closely related.

In order to have healthy and beautiful hair, you need a strong foundation to hold it in place. That is why it is so important to eat right, well and variedly, saturating your body with useful and necessary substances.

Due to the unsatisfactory ecology, most people are recommended several times a year to take vitamin and mineral complexes without fail, which will help to improve and strengthen the skin and hair. In some cases, experts advise taking complexes with a high content of vitamins A and E, for example, vitamin preparations such as Aevita.

It should also be remembered that the structure of the hair, its color, growth rate, and the number of follicles are genetically laid down by nature, therefore it is essentially impossible to influence such characteristics. That is why you cannot blindly trust an advertisement that promises to make your hair thicker and stronger almost at once. The main emphasis should be on a healthy diet and regular hair care.

Composition and structure

The composition of the hair is a large amount of a protein called keratin, a certain amount of water, some metals and minerals. In general, hair is a horny skin formation that is present only in mammals and homo sapiens. Their structure is best studied with a microscope. Hair has both inner and outer parts. In the outer part there are:

1. The core, which contains many non-keratinized cells.
2. The cortex called the cortex. It is in this layer that a lot of the substance "melanin" is contained, which is responsible for the color of human hair.
3. The outer layer, called the cuticle, is, on closer inspection, small scales that resemble shingles. In the presence of healthy hair, it is this layer that pleases the eye with its shine. The cuticle also protects the inside of the hair.

Natural antiseptic, which is included in the grease, is designed to protect the cortex from infections. The condition of the hair shaft directly depends on the environment in which a person lives. Various diseases can worsen the condition of the hair, since the access of the required amount of vitamins to them in this case is difficult.

Each hair grows from its own follicle. The root, in its shape, resembles a bag. Hair grows as long as its roots are alive, located in the scalp. A follicle is, in fact, a depression in which such a root is located. It expands downward and forms a hair follicle. It is to this part of the hair that the vessels and glands are connected, which ensure the processes of nutrition and the withdrawal of waste products. On the inner side of the follicle there is a hair nipple, which consists of very thin vessels, nerve and connective tissue. It must be remembered that the visible part of the hair is already dead, the living part is located directly under the scalp.

Hair thickness and amount

Having understood what the structure of the hair is, let's get acquainted with the functions of the hairline.

1. So, the first and main function is protective. Thanks to her, the scalp does not suffer from ultraviolet radiation emanating from direct sunlight.
2. Thermoregulatory function. It is on the human head that the hairline creates the optimal temperature for the brain to function. In the process of cooling, special muscles ensure the rise of the hair, and they prevent the rise of their own heat from the skin.
3. Touch function. It is the nerve endings on the scalp that make it sensitive to the slightest changes in the position of the hair. This is especially noticeable if some foreign body appears on the head.

Hair thickness and quantity are strictly individual characteristics. For example, the number of rods can vary from 100 to 150 thousand. The thickness depends on the color. Scientists have calculated that, on average, blondes have 50 microns, brunettes have 75 microns, and redheads have 100 microns. Curliness of hair depends on the location of the follicle in relation to the surface of the head.

The types of human hair are directly related to this, which can be:

• long;
• cannon;
• bristly.

Another classification divides human hair into the following types:

1. Fatty. In this case, there is an increased activity of the sebaceous glands and an excess of lubricant. An almost constant oily sheen is observed on the scalp, the hair can quickly become dirty and look unkempt.
2. Dry. On the contrary, the activity of the sebaceous glands is low. The skin is dry, the shaft is brittle, and the ends of the hair are often split.
3. Normal. As the name implies, in this case the skin condition is balanced.

In some cases, we are talking about the "transitional" type of hair.

At the same time, as a person gets older, the density of his hairline also changes in the direction of decreasing. To confirm this, a comparison of the hair pattern of a young man and a middle-aged man is sufficient. The length of one hair can reach 1 m. After that, the growth stops within 3 months. After this period, new follicles begin to appear. About 3/4 of all hairs develop and grow at the same time, and the rest 1/4 "rests". Healthy follicles are very tough and strong. They lend themselves to stretching by 1/5 of their length, after which they return to their previous state. Their strength is comparable to that of a metal such as aluminum. It is because of this that they are able to withstand heavy loads.

In addition, human hair is inherently very hygroscopic, that is, it can absorb moisture rather quickly. Due to this, the hairline is relatively resistant to weak acids, but follicles react poorly to alkalis.

In some cases, human hair can be used as an identifier because it has the ability to accumulate certain substances.

Little tricks when washing

When washing your hair, you need to massage the scalp with your fingertips to achieve better blood circulation. This will further stimulate the sebaceous glands, which create a natural protective layer on the hair. Better to use the shampoo 2 times.

For the first time, try to rinse the scalp itself, and the other time - the hair. It is better to apply the required amount of detergent to the palm of your hand and rub thoroughly so that it is applied evenly over the entire head.

Hair is an appendage of the skin, just like nails. Skin, hair and nails need to be taken care of as they are the main defenders against environmental damage. Do you know how a woman attracts, bewitches and bewitches all men without exception ?! Undeniably long, shiny, flowing strands of silk on their shoulders and back.

Isn't it true that a person, especially a woman, with thin hair or no hair at all is not particularly impressive. I'm not talking now about famous bald stars such as Fyodor Bondarchuk, Bruce Willis or Demi Moore in the movie "Soldier Jane". I'm talking now about ordinary women and men that we see every day.

What does the human scalp consist of?

Human skin on any part of the body consists of the same parts or layers, that is, the scalp differs little from the skin of the abdomen, for example. Click and view the picture below, which shows a section of skin and hair. As you can see, it consists of three layers:

• Epidermis
• Dermis
• Adipose tissue

Epidermis Is a thin protective layer of cells that is constantly renewed. The cells are arranged in several layers. The outer layers of cells in the form of horny scales die off and peel off, and new ones form below. this is how the update takes place. The epidermis plays a protective role, protecting the body from external influences of water, chemicals and ultraviolet radiation.

Dermis- This is the middle layer under the epidermis. It contains blood vessels, muscles, sebaceous and sweat glands, as well as hair follicles or hair roots. It is the dermis that determines the elasticity and tone of the skin.

Adipose tissue- also gives shape to the skin. The vessels pass through it and the lower part of the hair follicles is located.

What is human hair made of?

Hair, like trees, has its own trunk (shaft) and root. The hair shaft is located above the skin, and the root is located in the thickness of the dermis and ends in a hair follicle. The hair follicle is located in the hair follicle - the follicle, into the lumen of which the channels of the sebaceous glands open.

The secretion of the sebaceous glands gives the hair elasticity and shine. If there is little secretion, then the hair is dull and lifeless. But with excessive work of the sebaceous glands, the hair quickly becomes greasy and dirty. Thus, substances that lubricate human hair are formed in the sebaceous glands.

Each hair has its own muscles and innervation. Remember how the hair stands on end from fear or cold - this muscle contracts and lifts the hair. The effect of "goose bumps" is created, as in the photo below. Try pulling out one hair. It will turn out to be very painful, since the nerve endings are injured. This is why we feel the touch of our hair.

The human hair constitution has a complex structure. The chemical composition of the hair consists of:

• protein (80%)
• water (15%)
• pigments and other substances (5%)

Hair follicle structure

The hair follicle feeds on the vessels that go to the hair follicle located at the base of the bulb. Hair loss always occurs along with the hair follicle. Hair grows due to the growth and division of epithelial cells. If we examine the structure of the hair follicle under a microscope in a longitudinal section (click on the picture below), then three layers are clearly distinguished:

• cuticle
• cortex (cortex)
• medulla (medulla)

These layers are clearly visible in the anatomical structure of the hair shaft.

Cuticle- the outermost layer, consisting of a layer of keratinized scales, which are arranged like shingles, overlapping each other. The scales have a specific direction from the roots to the ends of the hair. The cuticle protects the hair from external influences. It is the cuticle that provides shine and silkiness to the hair. Each cell in the cuticle contains a fatty acid, which makes the hair water-repellent, and the scales are tightly adjacent to each other. When washing hair, it is not washed off, but it is damaged by chemical exposure.

Porous or glassy hair depends precisely on the properties of this layer, which are often given by nature. The porous structure of the hair is dry brittle hair that quickly absorbs dirt and chemicals. Vitreous hair is bouncy and dense.

Cortex (cortex) - is located directly under the cuticle and provides elasticity to the hair. Due to the peculiarities in the structure of this layer, people can have straight and curly hair, which in turn is genetically inherited. Thanks to the well-developed cortical layer, the hair can be curled and stretched. If this layer is insufficient, the hair becomes brittle.

The cortex is 90% composed of keratin - a protein that is part of the hair and is responsible for their strength. The remaining 10% is melanin, a pigment that provides natural hair color given by nature. Also in this layer there are air bubbles, which, mixing with the pigment, give a variety of hair shades. Look at the structure of hair at the molecular level below in the picture.

Brain layer (medulla) - is the core of the hair. In the animal kingdom, the medulla serves for thermoregulation. And in humans, the brain layer contains many voids and no longer performs the function of thermal protection.

Phases of hair growth on the head

Each cell of the human body undergoes periods of its birth, development and death. Likewise, old hair is constantly being replaced by new ones. How many hairs on a person's head on average? There are about 100-150 thousand hairs on the human head. Human hair growth rate is 1-1.5 cm per month. The average lifespan of a hair is about 4-6 years, i.e. a complete hair change occurs after a few years.

Each hair can grow continuously during this time until a dormant period occurs, which can last up to 3 months. As a rule, all hair in the resting phase then falls out. Approximately 90% of all hair is in the growing stage and 10% in the resting stage. Hair growth slows down with age, and this is considered a natural occurrence. All phases are shown in the picture below.

Each hair goes through 3 main growth phases:

• growth stage (anagen or anagen phase)
• intermediate stage (catagenic phase)
• resting stage (telogenic phase)

Hair development cycle

Hair growth in humans occurs in cycles. The cycle lasts for years, then there is a rest period for several months, after which the old hair falls out and a new cycle begins. Each hair follicle has its own development cycle.

The initial phase of active hair formation is called anagen, followed by a short transitional catagen and calm telogen phase, which ends the hair development cycle. In the telogen phase, the hair becomes flask-shaped, but does not fall out soon. As the hair grows, the papilla deserts, the cells of the bulb become keratinized, and the bulb turns into a hair bulb, similar to an inverted spruce cone.

The hair loss process lasts, according to some authors, 60-90 days; others say less. If there is a spike at the end of the hair that has fallen out, then this indicates a normal type of hair loss and that the hair is healthy. If, when pulling out, there is a dismemberment or notch at the root of the hair, it means that the hair is pathologically altered.

Such hair is brittle, their growth is weak, when they appear on the surface of the skin, they break off. The flask-shaped hair falls out during a physiological change of hair, in its place new hairs of the remaining papilla or of the newly formed papilla and bulb grow. With hair diseases, this process is absent, and the hair falls out completely. The duration of the individual phases of hair development in humans depends on the area of ​​the body where they are located and on their length.

On the scalp in adults, the duration of the anagen phase is 2-6 years; catagen phase - about 2 weeks; telogen phase - 3-4 months. About 85-90% of scalp hair is normally in the anagen phase, about 1% is in the catagen phase. The terminal growth phase elsewhere in the body fluctuates in relation to the telogen phase in this area. For eyebrow hair and ear canals, the anagen phase is 4-8 weeks; telogen - 3 months On the back of the hands, the anagen phase lasts 10 weeks; telogen - 7 weeks; the hair cycle in the beard area is about a year.

Hair properties

Growing healthy hair is usually strong and bouncy. The hair can be stretched 1/5 of its length, and after that it returns to its state. In terms of strength, they are comparable to aluminum and are able to withstand loads from 100 to 200 g. It is not surprising, therefore, that in the old days ropes were woven from women's braids, intended for lifting large loads.

Hair is hygroscopic, that is, it can absorb moisture. They are quite resistant to weak acids, but they do not tolerate alkaline compounds well. For humans, hair plays a big role. Firstly, they are a wonderful decoration that allows you to emphasize the charm, hide flaws, and secondly, they perform a number of important functions. Hair protects the head from overheating and hypothermia. Fluffy hair is involved in the sense of touch, eyelashes protect the eyes, hair in the nose and ears traps dust.

Hair has the ability to accumulate certain substances, which makes it possible to use them as an identifier. Forensic scientists have long successfully used this property of hair in their work.

Hair is of several types:

1) long (head, beard, mustache, in the armpits, on the genitals) - this is the strongest hair.

2) bristly (eyebrows, eyelashes, hair in the nose and in the external auditory canal);

3) cannon (on the skin of the face, trunk, limbs).

The part of the hair that is freely located above the skin is called the shaft (asarib), and the part hidden in the thickness of the skin is called the hair root (radix pili). The root ends with an extension - a hair follicle. Hair growth occurs in the bulb. From the connective tissue into the hair follicle protrudes the hair papilla, which carries the vessels that feed the bulb.

The hair shaft consists of three layers (Fig. 16). The core of the hair is called the medulla and contains keratinized cells. The medulla is absent in the vellus hair and at the ends of the rest of the hair.

The bulk of the hair is made up of its cortical substance, which is composed of elongated, tightly adjacent cells with an elongated core or traces of it, containing a pigment - a dye. The pigment can be red, yellow and black, and the combination of these colors creates an individual hair color. In the absence of pigment, the hair looks white.

The outer layer of the hair - the cuticle, the skin - is represented by flat, nuclear-free keratinized cells, which, being located in one layer, overlap each other like a tile.

The root part of the hair is located in the folliculus pili, which opens on the skin with a small extension (ostium). The excretory duct of the sebaceous gland flows into the skin follicle approximately at the border of the outer and middle third of the hair.

Hair growth and life cycle

In humans, each hair comes from a small but deep fossa in the skin - a hair follicle. The hair follicle is the hair root (hair follicle) with surrounding tissues that form such formations as the external and internal root sheaths and the hair-glandular complex (sebaceous and sweat glands, hair lifting muscle, blood vessels and nerve endings). The follicle develops as a small funnel-shaped fold of the epidermis, growing into the underlying dermis; at the bottom of which there is a papilla - an outgrowth of the dermis. This formation is called the vagina. The hair root is located in it, and it is surrounded by a connective tissue bag, and together they make up a mature hair follicle.

The papilla is rich in blood vessels that supply blood and nutrients to the follicle. The papilla controls the condition and growth of the hair - if the papilla dies, the hair dies, but if the papilla has survived, a new one grows in the place of the dead hair. Immature (stem) cells of the hair follicle are located above the papilla, they mature and divide inside the follicle. As these cells move upward towards the lumen connecting the follicle to the surface, they undergo a keratinization (hardening) process and become hair. Thus, the hair resembles a sprout that grows up due to the pressure that is generated during cell division.

Types and shape of hair

As we know, hair on our body is not everywhere the same in thickness, length and color. Therefore, there is a classification of hair by type and shape.

There are three types of hair:

• cannon,
• bristly
• long.

Fluffy hair cover the skin of the arms, legs and trunk. The vellus hair is soft, short (about 1.5 mm in length), non-pigmented and lacks medulla. These are the first hairs that appear on the body of the fetus during intrauterine development; they are also called "primary". Shortly before birth, this hair is partially replaced by pigmented hair. In the first years after birth, this type of hair on the scalp transforms into so-called intermediate hair, which, in turn, is replaced by terminal hair during puberty. The color of the intermediate and terminal hairs often does not match; in addition, terminal hairs are noticeably denser.

Bristly hair these are eyebrows, eyelashes and those that grow in the nostrils. They are quite tough, pigmented, but not long. By old age, this hair begins to grow in abundance on the face, mainly in men.

Long hair grow on the head, beard, chest, armpits and on the external genitals. Hair on the scalp undergoes several stages of development: their noticeable growth begins at the age of 2-3 years, and during puberty they acquire their final appearance. In the same period, pubic and armpit hairs are slightly modified - they become thicker and curly.

In normal cases, the distribution of hair on the body is dictated by gender, age, nationality. The shape of the hair depends on the shape and spatial location of the follicle, on the composition of the keratin of the hair shaft, on race and, ultimately, on individual characteristics. Averaging, we can say that the shape of the hair depends on the shape of the root.

There are three types of hair shape:

• smooth or straight,
• wavy and curly.

These three forms, in turn, have a number of subdivisions. Thick hair has the largest hair diameter. This is the strongest and most resistant hair, however, these bands provide significant resistance to any effect, including chemical. Therefore, usually the exposure time of cosmetic preparations on this type of hair is taken longer. Thick hair is generally more difficult to bleach, color and curl than thin to medium hair.

Medium hair is the most common group. It is accepted as the standard with which all other types of hair structure are compared. It is also worth noting that usually hair of medium thickness does not pose any particular problems with dyeing and other chemical procedures.

Thin hairs have the smallest diameter, which makes them very sensitive to any influences (thermal, chemical, mechanical). But at the same time they easily stain, branch off and change shape.

The distribution of pigment in hair depends on its structure. Melanin granules in thin hair are located more densely, so they change color faster and faster instead of natural pigment is artificial. However, the hair may appear darker than hair with a normal structure. Hair of medium thickness has an average reaction to coloring. Thick hair, on the other hand, takes on color very poorly and lightens for a long time, and when dyed similar to hair with a normal structure, it can give colors lighter than expected.

Determination of hair structure

The hair structure is determined on dry strands. Individual strands are selected on different areas of the head. Hold the strand with one hand and run your thumb and forefinger over the strand to feel the thickness of the hair. Usually this skill comes with practice. The structure (thickness) of the hair is not related to the shape of the hair, so curly hair can be either thin or thick hair.

Below are some general examples of different hair structures based on natural hair color or type. It should be noted, however, that this is only a general description and can be used to assist in determining hair structure and not as a substitute for a hair structure test:

1. Gray-haired: Thick, often described as coarse and wiry hair.
2. Redheads: Medium hair, examples were natural redheads.
3. Blondes: Thin hair, this structure is most common in natural blondes.
4. African Americans: Natural hair is usually thick and not elastic.
5. Asians: often thick and sleek hair, sometimes color-resistant.
6. Hispanics: Thick hair with a dark natural color.

Hair composition

The approximate chemical composition of healthy hair is as follows:

• 15% water
• 6% lipids
• 1% pigment
• 78% protein

If the hair has been exposed to chemical, physical influences, if certain hair diseases are found, their composition may change. For example, with frequent dyeing and perm, illiterate selection of hair care products, abuse of thermal styling methods - hair can lose a large percentage of moisture. The result of all these processes and actions is reflected in your hair not for the better!

in man

• fetal hair (prenatal);
• transitional (intermediate);
• cannon;
• long and bristly (terminal).

The embryos and vellus hairs are devoid of pigment and arise in a person already in the womb. Transitional hair is pigmented and appears before birth. In the first three years, the child's body is covered with light soft fluffy hair. Hair becomes more coarse in adolescence, hair appears in the armpits, in the groin area, on the face and body of men. Bristly hair is typical for eyebrows, eyelids, nostrils. There are all types of hair on the human head.

Video: Hair structure

Hair

"The Girl Picking Up Hair." Painting by Sophie Zhanjambre Anderson

Hair- an integral part of the protective cover, mainly in mammals, are phylogenetically derivatives of the epidermis of the skin. In animals, thick hair is called fur or wool. The so-called "hairs" (trichomes) are also found on various plant organs.

Structure

Scheme of the layered structure of the skin. The hair follicle is indicated.

The outer shell of the hair is formed by overlapping keratin scales. The visible part of the hair is called rod... The part of the hair under the skin is called hair root(or hair follicle). The bulb is surrounded by a hair follicle. The type of hair depends on the shape of the follicle: straight hair grows from a round follicle, slightly curly from an oval follicle, and curly hair from a kidney-shaped one.

Each hair is made up of three layers. The outer layer or cuticle has a protective function and is formed by thin cells like scales that overlap each other like roof tiles. When the cuticle scales lie tight, neatly overlapping, the hair is silky, soft and shiny. If the cuticle cells are physically or chemically damaged, the hair loses its shine, becomes brittle and easily tangles.

Under the cuticle is the cortex, a cortex made of elongated dead cells that give the hair its strength and elasticity. The cortex contains the pigment melanin, which determines the natural color of the hair. There is a medulla in the center of each hair, it consists of soft keratin cells and air cavities. The purpose of this layer is unknown, but it is assumed that it carries nutrients to the cortex and cuticle. This can explain the rapid change in hair with a disease.

The natural shine of hair depends on its own grease, including an antiseptic, which helps in the fight against foreign microorganisms. The skin contains sebaceous glands, they secrete their secretions into the hair follicles. As a lubricant, the secret gives excellent protection to the hair shaft, smoothing the cuticle surface and helping the hair retain moisture and maintain elasticity. The smoother the cuticle surface, the more light is reflected from the hair and the brighter its shine. Therefore, it is much more difficult to achieve the shine of curly hair than straight hair.

In some cases, for example, with excessive hormonal activity, when the sebaceous glands secrete too much secretion, the hair becomes oily. If there is too little secretion, the hair becomes dry.

Hair growth cycles

The living part of the hair is located under the epidermis. The hair that grows out from under it consists of dead tissue. There are three stages of hair growth.

The first is the stage of active growth, the second is intermediate, when the hair stops growing, but the papilla cells are functioning, the last stage is the complete cessation of growth.

Eventually, the old hair falls out due to the growth of the new one, and the cycle begins again. The first stage lasts from two to four years, the second stage lasts only 15-20 days, and the last one lasts from 90 to 120 days. At any given time, about 93% of hairs are in the first phase of growth, 1% in the second phase and 6% in the third. Scalp hair, which responds to hormonal stimulation in the same way as body hair, is genetically programmed to repeat the growth cycle 24-25 times during a person's life.

Hair types

Distribution of hair over the body of a woman and a man

There are three types of hair on the human body:

• Fluffy - thin, often colorless, covering the whole body, except soles legs palms, red border of lips.
• Rod - grow on the head, in men, after the onset of puberty, also on the face (see the article Beard).
• Axillary - Grows in the armpits and pubic hair (pubic hair).

They can also distinguish between three main types of hair: long, bristly and vellus.

Long

They are mainly located:

• On the head (vault of the skull, face).
• Axillary region.

The distribution is uneven. Most of all (90,000-150,000) - on the cranial vault (distributed with a frequency of 200-460 per cm²).

Blondes tend to have the most hair. Less - among brown-haired, brunettes and redheads (in descending order).

Bristly

They form eyelashes, eyebrows, grow in the nasal cavity and ear.

Ciliated hairs are relatively few in number. On average, eyebrows contain 600, eyelashes - 400 hairs.

Cannon

Cover the rest of the body.

Distributed at a frequency of 9-22 per cm². There are individual differences both in the number of such hairs and in the depth of the hair follicles.

Hair color

Figures and facts

Hair root

Hair in culture

Social status

In the Greco-Roman world, cutting hair was a sign of slavery.

In mythology and religion

Beliefs related to hair exist among almost all peoples. Hair has traditionally been considered a container of vitality, so young children are usually not cut until a certain age (usually three to five years). Among the Slavs, the first haircut was performed as a special rite, which was called "tonsure"; in the princely families, the boy was also put on a horse for the first time on the day of the tonsure.

Children were never shaved; always left at least a bunch of hair. In ancient Egypt, children were left with locks of hair on their temples or on the crown of their heads (the so-called "curl of youth"). In China, little boys had their hair cut so that bangs remained; the girls' hair was tied with a red thread.

In microminiature

Microminiaturists often use hair as an object of comparison. The most common microminiatures using hair: an inscription on the hair, an image on the hair, an image on a hair cut, a product inside the hair. Hair thickness (cross-sectional diameter) is always about 0.08 mm.

see also

Notes (edit)

Literature

Tolstoy N.I., Usachev V.V. Hair // Slavic antiquities. - Vol. 1. M., 1995 .-- S. 420-424.

Links

• Hairstyles, hair types, hair care. Materials are distributed under the CC 3.0 BY-SA license.

Wikimedia Foundation. 2010.

Synonyms:

Despite the fact that we are used to perceiving human hair as an aesthetic factor, in fact, from an anatomical point of view, hair is an integral part of the protective coat.

Hair structure

Each hair has a special structure. The outer shell of the hair is made up of keratin scales, which are superimposed on each other. The part of each hair that is located above the skin is called the shaft. Human hair structure three-layer ... The outer layer, also called the cuticle, has a protective function. It is formed by thin, overlapping scales. Accordingly, the structure of the human head hair is such that if these scales are laid tightly and correctly, then the human hair is soft, flowing and shiny. Both in the photo and in life, they look alive and beautiful. At the same time, if the cuticle cells are damaged (they can be damaged by both physical and chemical effects), the hair stops shining, gets tangled and breaks very easily.

The next layer of hair is cortex located under the cuticle. It is a crustal substance that gives elasticity to the hair. The cortex contains a special pigment, melanin, which determines what the individual hair color will be for a particular person. Inside each hair is the medulla, which is made up of keratin cells and air cavities. According to scientists, the structure of the hair shaft suggests that it is through this layer that beneficial nutrients come to other layers of the hair. To consider in more detail the features of the structure of the hair, a special graphic scheme can be used.

The part of the hair under the skin is usually called hair root (also called a hair follicle). The structure of the hair root is as follows: the hair root is surrounded by a hair follicle, the name of which is - follicle ... The particular form of the follicle observed in a person depends on the characteristics of his hair type. So, straight hair grows from a round follicle in a person, and hair of a slightly curly type grows from an oval follicle. People who boast curly hair have kidney-shaped follicles.

The general condition of the hair depends on the structure of human skin and hair. So, the natural shine of the hair determines the amount of its own grease, which includes a special antiseptic. In the skin there are sebaceous glands, the secretion of which is secreted into the hair follicles. This protects the hair shaft. Therefore, the functions of human hair also depend on how well such a lubricant protects each hair.

But sometimes the sebaceous glands produce too much secretion. This can happen under the influence of a splash hormonal activity , as well as due to other factors. As a result, a person's hair becomes very oily. In case of low production of such a secret, the hair, on the contrary, becomes too dry.

How hair grows

The part of the hair that grows out from under the skin of a person consists of dead tissue. The hair growth cycle lasts several years. After the old hair falls out, a new cycle begins again.

Hair growth is divided into three stages. On first stage hair grows actively. Second stage growth is called intermediate: at this time the hair is no longer growing, but the papilla cells are still functioning. On third stage hair growth stops completely. The functioning of the hair is arranged in such a way that under the influence of the growth of new hair, the old one falls out, after which the new hair goes through all the cycles again.

The first stage of hair growth can last 2-4 years, the second - about 20 days, the third - up to 120 days. If we evaluate all human hair as a whole at a certain moment, then approximately 93% of hairs are in the first phase of growth, 1% of hairs are in the second phase of growth, and 6% of hairs are in the third. Hair on the head and body can repeat its growth cycles 24-25 times throughout a person's life.

Hair grows all over the body, except for the soles and palms. An adult has approximately 100,000 hairs on its body. The amount of hair depends on what color they are. So, blondes have the most hair on the body.

Hair begins to appear in a person in the third month of intrauterine development of the fetus. There is uneven hair growth on the body. The hair grows most slowly on the eyebrows, the fastest growing is noted on the head. In three days, the hair on the head can grow by 1 mm. Normally, a person can lose 50-100 hairs per day. Hair loss in normal amounts is a physiological process. Human hair grows fastest in summer and spring.

Hair properties

Each hair contains 97% protein (keratin) and 3% moisture. Is a proteinaceous substance, which includes sulfur, vitamins, microelements. Several types of hair are identified that grow on the human body. Long hair is the most durable and grows on the head, as well as hair of the beard, mustache, genitals, armpits.

Bristly hair is the hair growing in the nose and ears, as well as eyebrows and eyelashes. Cannon hair grows on the skin of the arms, legs, trunk, face.

Healthy hair is bouncy and has a high margin of safety. Healthy hair is easy to stretch and can withstand up to 200 g of stress. Human hair is hygroscopic: it easily absorbs moisture. They are resistant to acids, but react very poorly to alkalis.

Most of the hair is located on the vault of the human skull. The eyebrows contain about 600 hairs on average, and the eyelashes have about 400.

If the functioning of the hair is determined by their properties, then the color depends on how the two types are related : eumelanin and pheomelanin ... These types of melanin are distinguished by the shape of the granules: in eumelanin, the granules are elongated, and the shape of the phaeomelanin granules is oval or round. Therefore, eumelanin is called granular pigment, and pheomelanin is called diffuse. All hair contains two types of pigments in different proportions. Hence, people have three different hair colors: redheads, blondes, and brunettes. But there are much more shades of hair color: there are up to 300 of them.

Hair functions

The function of the hair is very important for humans. First of all, hair is an adornment, that is, it performs an aesthetic function. They can both emphasize a person's dignity and hide his shortcomings. However, not only aesthetic functions are performed by human hair. They help to avoid both hypothermia and overheating of the head. A layer of air is created in the hair, which helps to retain both heat and cold. The fluffy hair, which is located on the body, takes part in the processes of touch. The hair that grows in the ears and nose helps trap dust. A person's eyelashes help protect the eyes. Armpit hair can reduce friction. Therefore, a person makes any movements, and the skin is not damaged. In addition, some substances can accumulate in the hair. This function is successfully used by criminologists in the process.

In general, the functions of hair in mammals are reduced to providing thermal insulation, protecting the skin from external influences, providing coloring (in animals, it is about camouflage and attractiveness). In addition, animals have special hair that allows them to navigate in space, that is, they are responsible for sensitivity. But in the process of evolution, human hair has partially lost such functions.