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The structure of hair and its types, the functions of human hair. How hair growth occurs, what it consists of and what it needs. What are the types of hair and how to care for them.
Function of hair in humans
Hair is an appendage of the skin consisting of dead keratin cells. Almost the entire surface of human skin has hair, with the exception of the skin of the lips and palms.
The biological function of hair is protective. Hair on the head prevents it from overheating and protects it in cold weather, as well as from mechanical stress (shock). Eyelashes protect eyes from getting foreign bodies(motes of dust, dirt), and the hair in the nostrils and ears intercepts foreign bodies and prevents them from entering the body. Eyebrows protect your eyes from sweat.
Chemical composition of hair
Approximate composition of healthy hair:
- 78–90% squirrel(keratin)
- 6% lipids(fatty acid)
- 3–15% water
- 1% pigment
The main chemical elements in hair are:
- carbon (49.6%)
- oxygen (23.2%)
- nitrogen (16.8%)
- hydrogen (6.4%)
- sulfur (4%)
- in microscopic quantities: magnesium, arsenic, iron, phosphorus, chromium, copper, zinc, manganese, gold.
Hair structure
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)
Video: Hair structure
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 fish or 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 - thanks 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 among people with different hair colors.
- On average, the total number of hairs on the head is:
- blondes – 140 thousand
- brown-haired – 109 thousand
- brunettes – 102 thousand
Hair begins to form in the hair follicles from the dermal papilla - the hair root. 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.
There are three stages of hair formation:
- anagen– period of hair growth, lasting from 2 to 7 years
- catagen– a period of regression during which cells stop dividing. The duration of the cycle is from 2 to 3 weeks.
- telogen– the resting phase, when the hair no longer grows, but is still retained in the hair follicle. During this phase, hair falls out easily. At the same time, approximately 10% of all human hair is in this phase. This is the hair that falls out when you wash your hair. The duration of the phase is up to three months.
Hair shape and color
Among the scales of the cuticle, and among the rods of the cortex layer, there are pigment granules 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.
Differences in hair waviness and thickness are due to the shape of the hair follicle. At straight hair, the follicles are located evenly and the hair grows perpendicular to the surface of the scalp. With wavy hair, the follicles have a slope, and with curly hair, they have a bend. As hair grows, it begins to follow the shape of its follicle and the resulting hair is either straight, wavy or curly.
The waviness of hair is also affected by the uniformity of cell formation during hair growth.
For straight hair, the formation of cells occurs evenly on all sides of the hair and as a result the hair has a round cross-section.
For wavy hair, cells are formed on different sides in unequal numbers, so in the section Wavy hair have an oval shape.
Curly hair When they grow, they first grow in one direction, then in the other. This occurs due to the fact that the formation of cells occurs alternately on different sides of the hair. In cross-section, wavy hair is kidney-shaped.
Hair types
The condition of the hair itself depends on the intensity of the work of the sebaceous glands of the scalp and on the state of the circulatory system of the scalp. The higher the secretion of sebum by the glands, the higher the fat content of the hair itself. Sebum spreads over the entire surface of the hair, covering it with a thin film. Depending on the “oily” content of the hair, it is divided into four types:
Characteristic signs hair depending on its condition (greasy)
| Hair type | ||||
| Normal | Fat | Dry | Mixed | |
| Greasiness and shine | moderate, healthy shine hair | are characterized by increased greasy shine caused by overproduction of the sebaceous glands | dry and dull along the entire length, due to insufficient functioning of the sebaceous glands of the head | oily at the roots, dry at the ends |
| Hair tips | normal | don't split hairs | dry, brittle, split ends | dry, split ends |
| Volume | normal hair volume | don't get frizzy | fluffy | medium volume, ends may become frizzy |
| Electrification | Sometimes | are almost not electrified | often, especially in low humidity | weakly electrified |
| Elasticity | flexible and elastic | good elasticity | brittle | elastic at the roots, brittle from the middle |
| Laying | pliable | can be styled, but stick together into separate strands | do not fit well, are constantly electrified and fluffy | holds the style, but fluffs from the middle to the ends |
| Hair washing frequency | every 2 – 3 days | daily | once a week | every 2 – 4 days |
- hair roots begin to form at the end of the third month intrauterine development fetus
- on the head, hair does not grow evenly - on the crown it is more dense, and on the temples and forehead less often
- average thickness human hair growing on the head ranges from 0.05 mm (blond) to 0.1 mm (red). In microns this would be between 50 and 100 microns.
- On average, one human hair can support a weight of 80 grams
- 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)
- in the summer and during sleep, hair grows faster
- 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.
Only truly healthy hair can look shiny and well-groomed. Often girls, wanting to help their curls, begin to care for them with the help of many expensive products, but do not receive desired result. This may be due to simple ignorance of the nutritional features of the scalp, the structure of vegetation and its roots.
By studying the structure of human hair on the head, you can more effectively nourish and grow it.
General information about hair and scalp
Every person's entire body is covered with tiny hairs. The only exceptions are the flexor surfaces, lips, lateral surfaces of the fingers, nail phalanges, palms and soles. In some places the hair is barely noticeable, in others it grows only in a certain color.
Before considering the structure of hair, you need to understand what functions its nutrient medium, that is, the skin, performs.
Structure of the scalp
Skin covers the entire human body, making up approximately 5% of body weight. On the head, this organ consists of several layers, which, in turn, are further divided into thinner formations.
1. Epidermis ( upper layer, consists of partially dead cells that are removed during the washing process):
Basal layer;
Grainy;
Brilliant;
Horny.
2. Dermis (upper layer containing blood vessels and nerve endings). It contains the famous protein collagen, which gives the skin elasticity and smoothness.
3. Hypodermis (subcutaneous tissue). Its main function is to provide thermoregulation.
Cells of the basal layer of the epidermis have two periods of renewal during the day: in the morning and in the afternoon until 15 hours. During this time, cortisol levels are low. This period is considered the most favorable for caring for the scalp and entire body.
Functions of the scalp
1. Protective. Sebum protects the body from harmful microorganisms entering it. The epidermis prevents mechanical damage.
2. Immune. T lymphocytes detect endogenous and exogenous antigens. Largenhans cells transport foreign bodies to the lymph nodes, where they are neutralized.
3. Receptor. The ability of the skin to perceive and recognize tactile and temperature stimuli.
4. Exchange. The skin breathes and also produces secretions through the sebaceous and sweat glands, creating a thin film on its surface.
5. Thermostatic. When the external temperature rises, the blood vessels of the skin expand, which increases heat transfer. A significant decrease in temperature forces blood flow to slow down and thereby reduce evaporation.
After studying the structure and functions of the scalp, it becomes clear that for normal hair growth you also need to have a healthy base that holds it. Its nutrition can be carried out in two ways: internal and external. Considering that the outer layer of the skin consists mainly of dead cells that no longer need food, it becomes important to supply it from the inside with vitamins and minerals. To do this, you need to eat right, and, if necessary, additionally take natural vitamin complexes.
Hair: structure and functions
Each hair consists mostly of the protein keratin. Also, the composition always contains some amount of water, traces of metals and minerals.
The structure of human hair
Hair is a horny formation of the skin. They are present only in humans and mammals. Thread-like formations cover part of the surface of the head.
You can study the structure of hair under a microscope. It is worth keeping in mind that when looking at the scalp, you cannot see everything. A very important part is hidden under it - the root. Therefore, when considering the structure of hair, you need to study its internal and external components. Read more about this.
Hair structure: outer part
Has three layers:
1. The core (inner part) contains non-keratinized cells.
2. Cortex (cortical layer) makes up 90% of the hair mass. Consists of elongated cells. This is where melanin is found, which is responsible for a certain hair color.
3. The cuticle (outer layer) in structure resembles the scales of a cone or tiles, where each subsequent part slightly coincides in area with the previous one.
These particles are arranged in 6-9 layers, which are attached using a certain composition. The scales grow from the root to the ends. It is this layer that shines so pleasantly when the hair is healthy, that is, all the particles lie flat and reflect light. Its main function is to protect the inner part of the hair.
The natural antiseptic contained in the fatty lubricant additionally protects the cortex from infection. The structure of the hair shaft depends greatly on the condition internal environment person. During many diseases, the condition of the hair deteriorates very quickly precisely because a sufficient amount of vitamins ceases to reach its inner and outer layers.
It is worth knowing that the core is not contained in all hair. For example, the light gun does not have it.
Hair structure: internal part
Each hair grows from its own follicle. It can also be called a matrix for cell growth.
The structure of the hair root resembles a pouch in shape. The hair will grow in length as long as its root, located in the scalp, is alive.
The follicle is a depression that contains the root. The “bag” expands downward, forming a hair follicle. Blood vessels, sebaceous and sweat glands approach this part. All of them provide nutrition and removal of waste products.
On the inside of the follicle there is a hair papilla, which consists of the finest vessels, nervous and connective tissue.
This is the structure of hair. The photo clearly shows this.
Functions of hair
1. Protective. During exposure to direct sunlight, it is thanks to the hair that ultraviolet radiation does not penetrate the skin.
2. Thermoregulation. Before the invention of warm clothing, people were protected from colds by their hair. On the head they maintain a comfortable temperature for normal brain function. This structure of human hair is no coincidence. When cooled, the erector muscles raise the hair and prevent its own heat from rising from the skin.
3. Touch. The large number of nerve endings in the scalp makes it sensitive to the slightest changes in the position of the hair. This can be especially noticeable when an insect crawls along it.
Hair growth stages
1. Anagen (2-4 years). At this time, the greatest activity of the follicle is observed, as intensive cell division and growth occurs. Due to this, hair constantly grows. In some cases, this stage lasts up to 5 years. In a healthy person, approximately 85-90% of hair is of this age.
2. Catagen (15-20 days). At this stage, the activity of the follicle decreases, but the cells of the papilla still function poorly. By the end of the period, the bulb is torn away from the feeding papilla. Only 1% of hair is in this phase.
3. Telogen (90-120 days). During this time, cells in the hair root no longer divide, and the hair follicle leaves its place along with the shaft.
After this, the anagen phase of the new follicle begins in the resulting free space.
The characteristics of growth also lie in the angle at which the rod grows. The structure of the scalp and hair together can produce a tube at an angle of 10 to 90°. This is why some women simply cannot do voluminous styling for themselves. This means that most of their hair grows at an angle of 10-20° and simply cannot bend in the opposite direction.
A similar problem in men manifests itself in inflamed areas on the face. They contain ingrown hairs that have never been able to rise above the surface of the skin.
The structure of hair on the head is slightly different from its counterparts in other places on the body. For example, they are able to withstand loads of up to 200 grams, this indicates their strength. The elasticity is evidenced by the ability to style hair in all kinds of hairstyles.
Hair thickness and quantity
The structure of a person's hair on the head is to some extent determined by its color. The thickness of the rod for redheads is approximately 100 microns, for brunettes - 75 microns, for blondes - 50 microns.
The number of rods on the head of different people is 100-150 thousand. This is determined genetically.
The shape of the hair, that is, the presence or absence of curls or simply waves, is determined by the location of the follicle relative to the surface of the head.
Thus, having studied the structure of human skin and hair, it becomes clear how to care for them, nourish them, style them and at what time it is advisable to do this.
SECTION 2study period:november
HAIR AND CARE:
TOPIC 2.1 Anatomy and physiology of hair
TOPIC 2.2 Hair care
STUDY PLAN TOPIC No. 2.1
Anatomy and physiology of hair
The structure of hair and scalp. Physiology of hair.
Hair in a person's life
Types of hair
Skin structure
The structure of the root part of the hair
Structure of the hair shaft
Hair growth and development
Hair types. Physical properties of hair.
2.2 Healthy and damaged hair
2.3 Basic characteristics of hair
2.4 Physical properties of hair
STRUCTURE OF HAIR AND SCALP.
HAIR PHYSIOLOGY
HAIR IN HUMAN LIFE
Hair decorates a person and plays an important role in assessing his appearance. Healthy, beautiful hair attracts the attention of others. Before learning about hair care, it is necessary to consider the structure of hair.
Hair covers almost the entire human body, it protects it from the harmful effects of the environment, retains heat in the body, and is involved in the sense of touch.
Together with the air between them, the hair forms an insulating cover, which protects the head from overheating and hypothermia, i.e. participate in thermoregulation.
Hair growing in the armpits protects the skin from abrasions, inflammation and infection. In addition, hair performs a tactile function, since the roots of the hair are connected to the nervous system in such a way that even very slight movement of the hair is immediately detected by this system.
The eyelashes are the most sensitive - they protect the eyes from excessive exposure to the sun, foreign bodies, pollution, and various small insects. The same can be said for stubbly hair in the nose and ears. The eyebrows form a kind of drainage channel for sweat flowing from the forehead, protecting the eyes from it.
Hair is capable of accumulating certain substances, which allows it to be used as an identifier. Forensic scientists have been successfully using this in their work for a long time. This same property of hair allows one to diagnose an excess or deficiency of certain elements of the periodic table during research.
In addition, hair is an important cosmetic component. First of all, they decorate the face, and modern hairdressers and stylists are able not only to emphasize charm, but also to hide flaws, if any.
Hair – these are horny formations of the skin, consisting of 80-95% of solid protein substance – keratin. The composition of the hair also includes water (10-13%), lipids, pigment (coloring matter), microelements (iron, copper, zinc, chromium, manganese).
The chemical composition of hair is carbon, oxygen, nitrogen, hydrogen and sulfur.
TYPES OF HAIR
There are three types of hair on the human body:
vellus hair - very thin and soft, covering almost the entire human body; they are not found only on the palms, soles and red border of the lips;
bristly hair – the toughest and shortest, these include eyebrows and eyelashes, hair in the nose and ears. In old age, this hair begins to grow in abundance on the face, mainly in men.
long hair
- grow on the head, beard, armpits, pubic area, and in men - on the face.
SKIN STRUCTURE
Since hair is an “appendage” of the skin, let’s look at the structure of the skin. Leather (from the Greek Derma – “skin”) is the largest human organ with numerous functions. The skin is closely interconnected with all organs and systems of the body.
Among the main functions of the skin, the following should be noted:
Protective: the skin protects underlying tissues from physical, chemical and biological influences
Thermoregulatory: subcutaneous fatty tissue and sweat glands provide regulation of body temperature
Excretory: sebaceous and sweat glands ensure the removal of waste products to the surface of the skin
Respiratory and gas exchange: the skin is permeable to gases and volatile liquids
Receptor: the skin contains sensitive nerve endings, through which we feel cold, pain, pressure, etc.
Epidermis
Dermis
Subcutaneous fat tissue
The epidermis, despite its small thickness, consists of five layers. The outer layer of the epidermis or stratum corneum, consists of a layer of aged and keratinized cells. They are constantly sloughed off from the surface of the skin and replaced by young ones migrating from the deep layers of the epidermis. The daily rate of loss of the stratum corneum is 10 - 14 g, which is approximately 675 grams per year. The deepest layer of the epidermis contains cells that produce pigment. melanin , which gives the skin a certain shade (from golden to dark brown). This pigment protects the skin from the action solar radiation, mainly from its ultraviolet part. Melanin formation is enhanced by exposure to ultraviolet rays. That's why we tan. Melanin is found in the skin, hair and iris of the eye.
Dermis (or the skin itself)- middle layer of skin. It is a strong plexus of fibers that determine the strength, elasticity and extensibility of the skin. These fibers are divided into two types: collagen and elastin.
The dermis contains blood vessels, nerves, receptors, muscle fibers, sweat and sebaceous glands, roots of hair and nails.
Sweat glands located almost everywhere skin. There are especially many of them on the skin of the palms, soles and forehead. Sweat glands secrete sweat, which, in addition to water (98%), includes chemicals formed as a result of metabolism occurring in the body, urea, uric acid, sodium chloride, etc. Sweating processes play an important role in maintaining normal temperature bodies. Excreted from the body with sweat a large number of harmful substances.
Sebaceous glands produce sebum, a fatty substance with a complex chemical composition. In an adult, the sebaceous glands produce 15-30 grams of sebum (1-2 tablespoons) during the day. Sebum is brought to the surface of the skin through the excretory duct. But most often the sebaceous glands are associated with hair. Their ducts open into the upper part of the hair follicle.
There are especially many sebaceous glands in the skin of the face, chest and back. They begin to function intensively during puberty. The amount of sebum secreted affects the skin type (dry, oily, normal) and, accordingly, the hair type. The activity of the sebaceous glands depends on gender, age, the state of the nervous and endocrine system, as well as from the nutritional structure.
The main function of the sebaceous gland is to lubricate hair with secretions and form on the surface of the skin. emulsion film(water-lipid film), which performs a protective function. It gives the skin elasticity, reduces friction of contacting surfaces; limits the evaporation of water from the surface of the skin, protects it from drying out.
Rice. Skin structure
Emulsion film has a very important for normal skin functioning. Due to the fact that the film has a slightly acidic environment, it prevents the proliferation of microorganisms on the surface of the skin.
What is pH? From a chemist's point of view, pH is a pH value or acid balance. This indicator indicates whether a given substance is acidic, neutral or alkaline.
The higher the pH, the lower the acidity. Neutral water (for example, distilled water) has a pH of 7. Anything less than 7 (up to 1) is an acidic environment, more than 7 (up to 14) is alkaline.
The surface of the skin is covered with a protective layer, which in most cases is characterized by a slightly acidic reaction at pH values of 4.5 -6.0. Therefore, at present, many people have an acid balance cosmetics is brought to slightly acidic, which coincides with the acidity of human skin.
Hypodermis,
or subcutaneous fat. The dermis passes into the subcutaneous fatty tissue, but there is no clear boundary of the transition. Subcutaneous fatty tissue is developed unequally in different parts of the body. The hypodermis is most developed in the abdomen and buttocks, especially in women. The subcutaneous fat layer, being a poor conductor of heat, protects the skin from cooling; in addition, it gives the body a rounded shape. Its thickness depends on age, gender, nutrition and lifestyle. It not only has thermal insulating properties, but also provides the body with energy.
STRUCTURE OF THE ROOT PART OF THE HAIR
Hair consists of two parts. The part of the hair that is freely located above the skin is called rod, and the part hidden in the thickness of the skin is root.
The root is located in the hair follicle. Hair follicle
– this is the hair root with the surrounding tissues. The length of the root part is 2.7-4 mm. The most expanded, lower part of the hair root is called hair follicle
. It is the only living part of the hair, is in constant division and determines hair growth. At the base of the hair follicle is hair papilla
. It is penetrated by nerves and blood vessels that supply the hair follicle. It is the hair papilla that is primarily responsible for the condition and growth of hair. The hair root also contains cells called melanocytes, which form the pigment melanin. It determines the color of our hair. 
The place where the hair exits the skin surface coincides with the place where the surrounding sebaceous glands exit. It's called hairy pores. The sebum released from the sebaceous gland lubricates the outer part of the hair, gives it elasticity, smoothness, and protects it from moisture loss. If little sebum is secreted, the hair becomes dull and brittle.
A small one approaches the root of the hair from the surface of the skin. hair muscle regulated by the nervous system. When the ambient temperature drops, a reflex contraction of these muscles occurs and tubercles appear on the surface of the skin (“ goose pimples"), the hair takes a vertical position, "stands on end."
We are born with a certain number of follicles, this value is genetically programmed. Therefore, the number of hairs we had at birth is the same amount of hair we will have on our heads throughout our lives.
STRUCTURE OF THE HAIR ROD
The hair shaft protrudes (grows) above the surface of the skin and consists of three layers:
Cuticle
Cortical layer
Core
Cuticle
- the outer layer of hair or it is also called scaly layer, resembles roof tiles. It consists of a layer of flat, colorless and keratinized cells ( scales) – from 4 to 12 layers. The scales fit tightly to the hair and lie in one direction. The cuticle performs a protective function and protects the hair. 
from adverse external influences
An intact, smooth scaly layer reflects light well: the hair is shiny. However, under the influence of light alkaline substances (for example, hair dyes), the scaly layer swells and the scales open. Under the influence of acidic substances (shampoos, balms), the scales close. If you frequently color your hair with aggressive products, the cuticle can be destroyed, and the hair becomes dull and brittle. Rice. Surface
healthy hair
Cortical layer or cortex, makes up more than 80% of the scalp, which means that there is no hairdressing procedure that would not have a greater or lesser effect on it.
The inner layer of hair can be compared to many thin threads (long spindle cells) twisted and intertwined with each other. These cells quickly become keratinized, filling with hard keratin. The cortex is responsible for the mechanical properties of hair - strength, elasticity, shape and structure.
The cells of this layer also contain grains melanin pigment, determining hair color. Melanin is divided into 2 types: eumelanin (black-brown) and pheomelanin (yellow-red). The whole variety of human hair colors depends on the ratio of these pigments. The formation of a certain shade of color is also influenced by the content of air bubbles in the cortical layer. The more such bubbles, the lighter the hair will be, and at the same time lighter. With age, the production of pigment at the hair root stops - the hair turns grey.
Core
(medullary substance or medulla) is the deepest layer of the hair. This is a soft spongy substance consisting of cells that have not yet been completely keratinized (keratinized). Through the core, like through a water pipe, nutrients rise into the hair. This layer contains air bubbles, due to which the hair has a certain thermal conductivity. The core is absent in fine vellus hairs and at the ends of other hairs. The core plays virtually no role in hairdressing operations and does not affect the properties of hair. But in animal hair it makes up 80% of the hair substance. This fundamental difference should be remembered when conducting various types of experiments with human or animal hair.
The hair shaft that we see is tissue that is not living. It is very important to handle and properly care for your hair, since the damaged scaly layer is not able to repair itself.
HAIR GROWTH AND DEVELOPMENT
Each hair follicle is an independent entity with its own growth cycle. In different follicles, these cycles are not synchronous, otherwise all our hair would fall out at the same time, while this process occurs gradually and imperceptibly.
There are three hair growth phases
:
Anagen (hair growth phase) is the stage of active growth. For long hair it lasts from 2 to 4 years
Catagen (transitional phase) is an intermediate phase when the hair stops growing, but the papilla cells function. Its duration is only 15-20 days
Telogen (resting phase) – complete cessation of growth. Lasts from 90 to 120 days.
Intrauterine hair formation, hair change throughout life. The formation of hair follicles occurs at 2-3 months of embryonic development. During intrauterine development, vellus hair initially covers almost the entire body, then its distribution changes. Germinal vellus hair (lanugo), which has no pigment and medulla, in recent months intrauterine development are replaced by other, often already pigmented hair (vellus).
At the 2-3rd year of life, another hair change occurs. Vellus hair remains on the trunk and limbs, but in the scalp they are gradually replaced by thicker and well-pigmented intermedial hair. At the beginning of puberty, intermedial hair is replaced by terminal hair, which may have a different color and shape than the hair of the previous generation. Hair growth on the body, in the armpits and on the pubis appears during puberty, as it is tightly controlled by sex hormones.
The most magnificent and Thick hair happen in adolescence, at 15 – 18 years old. Then, with age, the hair development cycle shortens, it becomes thinner, gradually depigmented (grey), loses strength, and grows more slowly.
HAIR TYPES
For literate and effective care it is important to correctly determine the hair hair type . Hair types usually mean: dry, greasy, normal and mixed hair. The oiliness of hair depends on the activity of the sebaceous glands, which in turn is purely individual and genetically determined. The oiliness of hair can be judged by skin type: oily skin grow greasy hair, on dry – dry.
Normal hair fit well and keep their shape for a long time; the scales are tightly closed, the hair is soft, elastic, and has a healthy, vibrant shine.
Dry hair difficult to install. Because they have strong keratin fibers. Due to the weak functioning of the sebaceous glands, the hair does not receive natural lubrication, as a result of which it looks dull, faded, easily tangled, electrified, scattered and difficult to comb. Dryness can be caused by choosing the wrong shampoo, frequent bleaching, constant coloring, or prolonged exposure to the sun.
Greasy hair unlike dry ones, on the contrary, they arise as a result of excessive active work sebaceous glands, so they look sticky, “greasy”, wet hair. It is difficult to regulate the functioning of the sebaceous glands; it is easier to influence the hair from the outside: touch less with your hands, do not use hot water when washing, dry your hair with a hairdryer in cold air mode, apply highlights all over your head.
Mixed type
hair is characterized by the presence of oily roots and dry ends. The reason for this may be improper care for hair.
HEALTHY AND DAMAGED HAIR
When starting to work with hair, you need to get as much full information about their condition. Think about it. How often do you meet people with really healthy, beautiful hair? Hardly. In practice, most often you have to deal with damaged hair.
Healthy hair – soft, shiny and obedient. The cuticle cells are arranged in even layers like tiles, making the hair manageable and soft to the touch. The smooth surface of the cuticle reflects light rays, making hair look shiny.
Damaged hair – the exact opposite of healthy. They are dull, tough and unruly. This occurs due to the fact that the order of the cuticle scales is disrupted. They rise and become brittle, as the cells of the superficial layers of the cuticle become coarser and cling to each other upon contact. The softness of the hair decreases significantly and it becomes unruly. The cuticle does not reflect light well, causing hair to look dull.
Sometimes the harmful effects can lead to complete destruction of the scales, resulting in split ends of the hair. If the cuticle is broken in the middle of the hair, then it breaks.
There are three type of hair damage
:
mechanical (too frequent combing, scratching, etc.);
thermal (hair drying as a result misuse hair dryer, tongs, hot rollers, etc.);
chemical (frequent perms, bleaching or dyeing hair).
Thermal damage. The moisture content of your hair is important for its health and therefore its appearance. Loss of moisture makes hair less elastic and more susceptible to mechanical damage. When the hair is heated strongly (in the dryer, when using electric curlers, hot rollers, or a hair dryer at maximum temperatures), the keratin softens and the water begins to evaporate quickly, causing increased formation of bubbles on the hair shaft. Thus, contributing to its destruction. There are no means to combat this. But regular trimming damaged hair reduces the likelihood of their ends splitting. When drying your hair or styling your hair with a hairdryer, the temperature should fluctuate within 60C - then significant, unfavorable changes in the hair are not yet possible. Only at a temperature of about 75 C does the strip undergo rapid deformation, weakening its elasticity and resistance to mechanical stress.
Modern electric hair curlers have a built-in thermostat or heating coil, which does not allow the working part to heat up to temperatures above 80 C. This completely guarantees the safety of hair operations.
One of the negative factors affecting hair is excessive exposure to sunlight. This manifests itself in natural discoloration (burnout) and leads to a decrease in hair strength. They become more rigid and porous, requiring appropriate care procedures. 
Rice. Type of damaged hair(split ends of hair; creases from a tight elastic band; damaged outer layer of hair; split hair)
MAIN CHARACTERISTICS OF HAIR
The main characteristics of hair include: color, density and density of growth, length, thickness and stiffness, strength and elasticity, porosity and shape of the hair.
The structure and composition of hair allows us to divide them into four ethnic groups :
1. Eurotype group characterized by a wide variety of types and widespread. Representatives of this race may have pale skin, like northeastern Europeans, and dark-skinned, like the natives of subcontinental India. Hair can be straight and wavy, thick and thin, of different colors and shades - from black to light brown.
2. Caucasian group– mostly have wavy hair. They are rigid in their structure.
3. Mongoloid group– have thick and coarse hair. Most often, straight and sometimes slightly curly. Mostly hair is long and dark in color.
4. Negroid group– characterized by very tight, fine hair and, as a rule, very dry.
Attitude to one group or another largely determines the condition and properties of hair.
Hair color. Hair color depends on many factors, the most important of which are genetic and endocrine.
Hair color is usually related to skin color, which is determined by the same pigment - melanin. The spectrum of human hair colors is determined by two types of melanin: eumelanins black and brown colors dyeing hair in dark colors(black and chestnut), and pheomelanins yellow and red colors, giving the hair light warm shades
The main hair color and its shades are also determined by the content of air bubbles in the cortical and core layers of the hair. Blonde hair Compared to dark ones, they contain a larger number of air bubbles, and gray ones are completely filled with them. The following are distinguished: natural colors hair
:
black – characteristic of the Mongoloid and Negroid races;
dark - typical of the European race and Mediterranean inhabitants;
chestnut - typical for residents of the middle zone;
light - typical for people living in the North;
red - found most often among the Anglo-Saxons;
gray hair is a consequence of atrophy of the natural dye.
If there is no natural pigment in the hair, then they talk about so-called albinism.
The following are distinguished: hair shades
:
ashen
golden
orange
red
Hair is divided into different color groups : blond, brunette, brown-haired and red.
1. Blond– all those whose hair is fairly light in color. These are ash (light brown), wheat and golden hair.
2. Brunette– from bright black to brown.
3. Brown-haired– have shades from dark blond to chestnut.
4. Ginger - golden copper and all red shades.
To determine hair color, special scales have been created from straight natural or artificial hair. Hair color is also determined using reflected light spectrophotometry.
Hair porosity- This is their ability to absorb moisture.
At low porosity hair is moisture resistant. The cuticle is dense, as a result of which moisture and chemical compounds penetrate into them poorly, and the hair requires longer processing.
At medium porosity the cuticle is slightly raised, the hair is normal and requires an average processing time to color it.
In hair with high porosity the cuticle is strongly raised, the hair quickly becomes colored, but also fades quickly.
Hair with low porosity does not absorb moisture well, which creates some difficulties when coloring and curling such hair. Excessive porosity makes hair dull, depriving it of shine and vitality. This type of hair requires treatment.
Hair shape. Hair shape depends on shape and spatial location of the follicle, from the composition of the keratin of the hair shaft, from race and, simply from individual characteristics its owner.
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The structure and location of the hair follicle
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Straight hair |
Wavy |
Curly |
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Direct |
With an inclination |
With bend |
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Hair section
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There are three types of hair shapes (picture on the right): smooth or straight (1-3), wavy (4-6) and curly (7-9) - more common in people of the Negroid race. In its turn smooth hair divided into: smooth (1), tight (2), flat-wavy (3); wavy into: wide-wavy (4), narrow-wavy (5), curly (6); curly into: curled, slightly curly (7), highly curly (8), weakly spiraled and strongly spiraled (9). On the cut smooth hair forms a circle, wavy - an oval, curly - a flattened oval (diagram above).
Hair shape, like natural color may change with age. Straight hair can become wavy and vice versa. Basically, the change in hair structure occurs unevenly throughout the head. For example, at the back of the head the hair becomes wavy, while the rest of the hair remains straight. Unfortunately, many women's hair, over time, only slightly changes its structure. For example, from flat-wavy (3) to wide-wavy (4) and then unevenly throughout the head. Many people believe that hair changes due to the use of different chemicals(dyes, perms), but this is not so. Only the structure of the upper part of the hair changes, internal structure this does not change. Having permed straight hair, the hair roots, while growing, remain straight. Why keratin-secreting cells change their distribution around the root over time is not yet known. There are many theories that this is influenced by hormonal changes, nervous shock and individual characteristics of the body. Most likely, all of the above factors influence this change.
Hair thickness and hardness (hair texture)
.
Hair can be thick, medium-thick and thin, also divided into very hard, medium-hard and soft.
Since hair is an appendage of the skin, first of all, it is directly dependent on the skin. There is a dependence: the thinner a person’s skin, the thinner hair and vice versa. Hair thickness also depends on a person's ethnicity, age, and color. The Asian ethnic group has the thickest and coarsest hair. The thickness of the average European's hair ranges from 0.04 - 0.06 mm.
Hair thickness changes as a person ages. An adult's hair is approximately 2-3 times thicker than a newborn's, but in old age the hair becomes thinner again.
Depending on the color, redheads have the thickest hair, brunettes have thinner hair, brown-haired people have even thinner hair, and blondes have the thinnest hair. For example: for blondes the hair diameter is 0.03mm, for brunettes – 0.05mm, for redheads – 0.07mm . In addition, the hair at the temples is thinner than at the back of the head.
Hair keratin is responsible for the structure of hair and its rigidity. Coarse hair, as a rule, have a larger diameter of hair strands, medium - medium, soft - small diameter of strands.
The thickness of the hair affects the volume of the hairstyle. The thicker the hair, the more voluminous the hairstyle looks. The softness or hardness of the hair has a greater influence on the quality of manageability during styling. How softer hair, it’s easier to lay them there.
Hair density. Growth density. The number of hairs on the head in an area of 1 square. cm (hair thickness) varies depending on the individual characteristics of the body, race, hair thickness, location. The thicker the hair, the less there is.
The average number of hairs on a person's head is:
For blondes - 140 - 150 thousand;
Brown-haired people have 110 thousand pieces;
For brunettes - 100 thousand;
For red-haired people - 50 - 80 thousand pieces.
The hair density is not the same on different parts of the head. On the parietal part the hair is thicker (250-350 pieces per 1 sq. cm), and on the occipital part and on the temples it is sparse (150-250 pieces per 1 sq. cm).
It's no secret that a person's hair falls out and grows back throughout life. Every day we lose from 30 to 100 hairs - this is absolutely normal and almost unnoticeable. Normally, these losses are replenished, but with pathological loss, self-healing does not occur, i.e. talk about baldness (or alopecia).
Hair is better preserved on the back of the head and on the sides of the head because blood flows to these areas more actively. In addition, these areas contain thin layers of fat and muscle that prevent the blood vessels from constricting. The temples, forehead and crown contain a fairly thin layer of fat and do not have muscle fibers. As a result of stress or tension, the skin tightens sharply, which leads to a narrowing of blood vessels, and therefore blood begins to flow poorly to the papillae, which in turn can lead to baldness.
Scientists have proven that the fullest hair grows by the age of 30. From 30 to 50 years, the amount of hair decreases sharply, after which it may remain unchanged.
Hair length The length of hair (uncut) primarily depends on belonging to a particular ethnic group: representatives of the Mongoloid (Asian) ethnic group have the longest hair, and representatives of the Negroid (Negro) ethnic group have the shortest. Europeans have average hair length.
Length short hair reaches 20 cm, this is mostly short haircuts. Medium hair from 20 to 40 cm. With such hair you can model different hairstyles. Long hair over 40 cm. With such hair you can model large complex hairstyles for formal evenings, as well as avant-garde hairstyles
The length of the hair also affects its quality. The ends of long hair tend to be super porous. In general, the longer the hair, the lighter and coarser it is at the ends. The length of the hair itself depends on many factors. Some people have hair that grows below their shoulders, while others grow it to their waist. The longest hair - 7 m 89 cm - was that of Swami Pandarasande, the caretaker of the Indian monastery
The normal hair growth rate is approximately 0.3 - 0.35 mm per day. In one day, if you calculate the total increase in hair length, a person’s hair increases by about 30 m. In the morning and evening, hair grows faster than at the rest of the day. At night, hair grows very slowly or does not grow at all. The longest hair grows between the ages of 13 and 17, and then with each subsequent hair change it becomes shorter and thinner.
PHYSICAL PROPERTIES OF HAIR
The physical properties of hair are strength, elasticity, ability to absorb water, electrical conductivity and resistance to biological and chemical influences (stability).
Strength. All hair has considerable strength and breaks when fairly heavy weight is applied. . In terms of strength, they are comparable to aluminum and can withstand a load of 100 to 200 g. Straight hair has greater strength, curly hair has less strength. This property of hair changes with age, first increasing, and then, with old age, decreasing.
Human hair is stronger than lead, zinc, platinum, copper and is second only to iron, steel and bronze. A woman's braid, consisting of 200 thousand hairs, can hold a load of up to 20 tons. It is not surprising, therefore, that in the old days ropes were woven from women’s braids, intended for lifting large loads.
Elasticity. Healthy hair that grows is usually strong and resilient. Hair elasticity is the ability of hair to withstand bending, compression and tension without breaking. Elasticity depends on the thickness of the middle layer of hair (the thicker it is, the more elastic and stronger the hair), as well as on the condition of the hair. Healthy hair is so elastic that in a dry state it can stretch 20-30% of its length and then quickly return to its original state, and in a wet state by more than 50%.
The elasticity of hair undergoes significant changes if its shape has been subjected to changes in the heat. New form In such cases, due to prolonged loss of elasticity, the hair remains for a long time (the principle of hot perming is based on this).
If your hair has low elasticity, then most likely it needs moisturizing.
Stability. The hair is very durable and highly resistant to mechanical, biological and chemical influences. True, with age, the strength of the hair decreases.
Resistance to biological influences lies in the hair's significant resistance to decay. Chemical resistance means that the hair structure does not change when exposed to weak acids and weak alkalis. When exposed to an acidic environment, the scales of the outer layer of the hair “close”, and when exposed to alkaline compounds, they “open”, and the stronger the alkaline composition, the more destructive it affects the structure of the hair: the scales of the outer layer open and, being partially deformed, no longer close; hence the inner layers of the hair are not protected and are subject to the harmful influence of the external environment. Particularly severe burns to the hair and scalp occur when the execution technology is violated. perm and hair coloring (bleaching). For example, under the influence of hydrogen peroxide, hair becomes thinner (this property of hair is taken into account when removing vellus hair).
Hygroscopicity. Human hair is hygroscopic - the ability to absorb moisture, as well as glycerin, animal and vegetable fats. It should be remembered that dry hair, absorbing clean water, swells and increases its volume in cross section by approximately 15%, and in length by approximately 17%. This deformation is temporary; they return to their previous length and thickness as they dry.
Substances such as mineral oils do not penetrate into the hair and remain on its surface. Vaseline oil and Vaseline.
Electrical conductivity. Hair is characterized by good electrical conductivity; for example, when combed in a dry state, it easily becomes electrified.
So, the condition of our hair depends on the following factors: heredity, health, age, gender, hormonal balance, climate, etc.
All acute, colds, infectious diseases, as well as chronic diseases, physiological changes in the body associated with puberty and pregnancy, affect the condition of the hair. During these periods, dryness, thinning, brittleness and hair loss may occur. Diseases of internal organs also often manifest themselves on the skin and hair, and, conversely, skin diseases affect the general condition of the body.
However, the appearance of our hair largely depends on ourselves: what we wash it with, how we care for it, and whether we chose the right haircut. Modern products allow you to curl and straighten your hair, change its color, and influence porosity and elasticity. In general, no matter what kind of hair nature gives you, 90% of it depends only on you and your efforts whether it will look luxurious or dull.
INTERESTING FACTS ABOUT HAIR
Hair grows at a rate of 0.35-0.40 millimeters per day. During the day, our hair lengthens, if we count the total increase in hair length, by thirty meters. 12 centimeters per year, 7.6 meters throughout life
A beard consists of 7-15 thousand hairs. And it grows at a speed of 14 centimeters per year.
The hair of red women has technical applications - they are used in hygrometers, devices for determining air humidity. The action of a hair hygrometer is based on the property of defatted hair to change its length when air humidity changes. Red hair is best suited for this purpose.
A woman's braid consists of an average of two hundred thousand hairs and can withstand a load weighing 20 tons.
90% of hair is constantly in the growth stage, 10% is in the loss stage.
Hair grows faster in summer and during sleep, and also between the ages of 16 and 24.
From each hair follicle, about 20–30 hairs grow sequentially throughout life.
Hair loss affects 60–70% of men and only 25–40% of women.
Every day, from 50–80 hairs fall out in children and up to 100–200 hairs in adults. If it is more, this is already a reason to turn to specialists.
The strength of hair is comparable to aluminum. One hair can withstand a load of 100 to 200 grams.
The hair can be stretched to 1/5 of its length, and after that it returns to its original state.
The lifespan of hair varies: on the head of men it lasts an average of two years, on women it lasts four to five years (maximum 10 years).
The average density of hair “planting” is 250–300 pieces per square centimeter.
The condition of the hair directly depends on the mood: when a person is elated, the hormone of happiness is released - endorphin, which has a beneficial effect on the entire body, including the hair. But stress spoils it, making it brittle, split and lifeless. It’s not for nothing that people say: “Hair curls out of joy, but splits out of grief.”
Contrary to the belief that long hair is the prerogative of women, the main “long-haired people” are still men: the Indian monk Swami Pandarasande at the beginning of the twentieth century wore a braid seven meters 89 centimeters long. The longest hair among women is American Diana Witt: 259 centimeters.
The length of hair on the head that a person grows during his life is on average 725 kilometers.
Blondes have the most hair on their heads - about 150,000. Brunettes have 100,000, and redheads have even less - about 80,000.
SELF-TEST QUESTIONS
How would you determine the functions of hair?
What does hair consist of?
What layers does the skin consist of?
List the functions of the skin.
What is the root part of the hair?
What is the hair shaft?
List the main types of hair?
What are the main phases of hair growth?
What are the types of hair and their characteristics?
Indicate the signs of healthy and damaged hair. What types of damage do you know?
Specify the criteria by which the hairdresser diagnoses the condition of the hair.
Tell us about the physical properties of hair.
SITES AND ADDITIONAL INFORMATION FOR SEARCHING ON THE INTERNET
Konstantinov A.V. "Hairdressing: Practical guide" - Moscow: Higher, 1987 - p. 336
Trichology. The science of hair and scalp.
Hairdressing theory. Hair Science.
Hairdressing tutorial
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 actions of professional and folk remedies for hair are aimed.
Scalp
The scalp can cause hair problems. Thus, its excessive production of sebum leads to the fact that the strands quickly get dirty, stick together, and seem stale. Insufficient production, on the contrary, leaves the curls defenseless against environmental influences, because a protective film is not created on them.
The skin has three main layers:
- Epidermis (external);
- Dermis
- 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, similar to 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, which 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:
- Taking certain medications;
- Performing certain medical procedures and manipulations;
- Coloring, lightening, tinting hair;
- Frequent and intense heat treatments (blow-drying, straightening, curling, etc.);
- Chemical treatments, both positive and negative (masks, balms, perm/straightening);
- Bad habits (smoking, alcohol);
- Eating disorders, diets;
- Changes in metabolism.
Normal chemical composition hair is an important rule for 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.
WATCH VIDEO INSTRUCTIONS
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 its 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.
Hair papilla- large education, responsible for the growth and life of hair. When removed, if it survives, it will soon grow new hair. 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 of 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. Smoothness, shine and appearance depend on it. 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 microscopeCortex 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, nor to the structure. In fact, it is not needed. Responsible only for the thermal conductivity of the strands. There are also no chemical processes in it.
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.
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 the natural adornment of any woman. Curly and straight, voluminous and smooth, long and short, light brown and chestnut - what does all this diversity depend on? First of all, it depends on the structure and composition of the hair that is given to us from birth.
Hair structure
The structure of hair is not as simple as it might seem. Each hair consists of a visible part - the shaft - and an invisible part, immersed in the skin - the root. At the bottom of the root is the source of life of the hair - a small papilla permeated with nerves and blood vessels.
Through this papilla, the hair is nourished and maintained. From here the hair begins to grow. The entire hair root is enclosed in a hair follicle.
The number of follicles is genetically determined in us, so the number of follicles we have at birth is the amount of hair we will have on our heads throughout our lives. The number of hairs ranges from 80 thousand for redheads to 150 thousand for blondes. Moreover, there are more of them on the crown than at the forehead and temples.
The deepest expanded part of the root is called the bulb. The place where the hair exits the skin surface coincides with the place where the surrounding sebaceous glands exit. It's called the hair pore. The sebum released from the sebaceous gland lubricates the outer part of the hair and maintains its elasticity. If little sebum is secreted, the hair becomes dull and brittle.
A small hair muscle, regulated by the nervous system, approaches the hair root from the surface of the skin. When this muscle contracts, the hair takes on a vertical position and “stands on end.” This is especially noticeable when a person is afraid.
The hair shaft, which gives each of us a unique look, consists of three layers:
- The outer layer is the cuticle. It consists of 7-9 rows of horny plates arranged in the form of tiles. In the “open” state of the hair, the scales are arranged loosely and move away from the surface. In the “closed” state, the scales are pressed to the surface, the hair becomes denser and acquires shine. Under the influence of alkali (soap), the hair swells and opens its scales, and under the influence of acid (rinse aid), it “closes.”
- The middle layer is the cortex. It gives hair flexibility, elasticity, and contains the pigment melanin, which determines its color. Melanin does not dissolve in water, but interacts with alkalis and acids. In older people, the pigment disappears and the hair turns gray.
- The last layer is the medulla. The deepest layer, the pulpy, medullary, consists of incompletely keratinized cells. It may be absent in extremely thin hair.
The texture of the hair is determined by the diameter of the shaft, depending on which the hair is divided into thick, medium and fine.
Hair porosity- This is their ability to absorb moisture. Hair with low porosity does not absorb moisture well, which creates some difficulties when coloring and curling such hair. Excessive porosity makes hair dull, depriving it of shine and vitality. This type of hair requires treatment.
Elasticity is the ability of hair to withstand bending, compression and tension without breaking. Springy, vibrant, shiny hair with normal porosity has great elasticity and, when wetted, can increase its length by 20%.
The length of the hair also affects its quality. The ends of long hair tend to be super porous. In general, the longer the hair, the lighter and coarser it is at the ends. The length of the hair itself depends on many factors. Some people have hair that grows below their shoulders, while others grow it to their waist. The longest hair - 7 m 90 cm - was that of Swami Pandarasande, the caretaker of the Indian monastery.
The structure and composition of hair allows us to divide them into three ethnic groups:
- Caucasoid. Such hair can be of any color, straight and very curly, very thin, medium and thick.
- Mongoloid. Such hair is often straight, sometimes wavy, thick, and mostly dark.
- Negroid. This type of hair is curly and varies in thickness.
Hair composition
The chemical composition of hair is well known: carbon, oxygen, nitrogen, hydrogen and sulfur. The main components of hair are keratin and melanin. Keratin, being a dense protein, promotes keratinization of hair cells, and melanin, being a pigment, affects their color. Hair also contains some amount of fatty substances, cholesterol, mineral compounds and arsenic.
Replacing an old hair with a new one occurs when the active cells of the papilla cease to function. The bulb begins to increase in diameter and is gradually pushed out. This is how the hair falls out. At the same time, new active cells are formed in the hair follicle, giving life to new hair. Hair change is a normal natural process if 30-50 hairs fall out on your head per day.
Not only the amount of hair is genetically determined in us. Their color and structure are also determined by heredity. But despite this, the appearance of our hair largely depends on ourselves: what we wash it with, how we care for it, and whether we chose the right haircut. Besides, modern means allow you to curl and straighten hair, change its color, influence porosity and elasticity. In general, no matter what kind of hair nature gives you, 90% of it depends only on you and your efforts whether it will look luxurious or dull.
