On the structure and functioning of the hair

June 4, 2013

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Despite the fact that we are accustomed to thinking of human hair as an aesthetic factor, in fact from the point of view of the anatomy of the hair are part of the protective cover.

Hair Structure

Each hair - a special structure. The outer shell of hair is keratin scales, which overlap each other. That portion of each hair that is above the skin, called a pivot. The structure of human hair three-layer . The outer layer, which is also called the cuticle, is designed to perform the safety function. His form thin flakes, overlapping each other. Accordingly, the structure of the hair of the head in humans is that if these scales are stacked firmly and correctly, the human hair soft, flowing and shiny. And in the photo and in life, they look alive and beautiful. At the same time, damage to the cells of the cuticle (they can damage both physical and chemical effects) hair cease to shine, very easy to get confused and broken.

The next layer of the hair - cortex Located under the cuticle. That cortex, which gives the elasticity of the hair. The cortex is a special pigment called melanin, which determines what the individual hair color in a particular person. Inside each hair is the medulla, which make up the keratin cells and air spaces. According to scientists, the structure of the hair shaft is assumed that this layer comes useful nutrients to the other layers of the hair. In order to more fully consider the characteristics of the structure of the hair, can use a special flowchart.

A piece of hair, which is under the skin, called the hair root (also called hair bulb). The structure of the hair root as follows: the root of the hair is surrounded by hair follicles, whose name - follicle . On which form of the follicle is observed in humans, depend on its particular type of hair. So, from round follicles in humans grow straight hair and curly hair is a little oval-type grow from the follicle. For those people who can boast of curly hair follicles kidney-shaped.

From that, what is the structure of the skin and hair of a person depends on the overall condition of the hair. So, the natural shine of the hair determines the amount of own fat grease, which includes a special antiseptic. In the skin has sebaceous glands, the secret of which is released into the hair follicles. This ensures the protection of the hair shaft. Therefore, the functions of human hair also depends on how well such a lubricant protects each hair.

But sometimes the sebaceous glands produce too much of a secret. This may occur under the influence of the burst hormonal activity And also due to other factors. As a result, a person's hair becomes very greasy. Provided that such low product secretion hair conversely become too dry.

As the hair grows

The part of the hair that grows out of human skin consists of dead tissue. The cycle of hair growth lasts for several years. Once the old hair falls out, a new cycle begins again.

Hair growth process is divided into three stages. In   first stage   hair grows actively.   Second step called intermediate growth: this time the hair is not growing, but the papilla cells are still functioning. In   third step   hair growth stops completely. The functioning of the hair is arranged so that under the influence of the growth of new hair, old fall, after which the new hair again goes through all cycles.

The first stage of the growth of hair can last 2-4 years, the second - about 20 days, and the third - to 120 days. If we evaluate all the hair the whole person at a certain point, approximately 93% of hairs are in the first phase of growth, 1% of the hair going through the second phase of growth and 6% of the hair - the third. Hair and body hair growth cycles can be repeated throughout a person's life 24-25 times.

Hair grows all over the body, only exception is the sole and palm. An adult body has about 100,000 hairs. The amount of hair depends on what color they are. Thus, most of the hair on the body of blond.

Hair begin to appear in humans in the third month of fetal development. The body is marked uneven growth of hair. The slowest growing hair on the eyebrows, the fastest growth is noted on their head. For three days the hair on your head can grow to 1 mm. In a normal day, a person may fall 50-100 hair. Hair loss is a normal number of physiological processes. The fastest way to grow human hair in the summer and spring.

Properties Hair

The structure of each part of the hair 97% protein (keratin) and 3% moisture. Keratin   - A protein substance, which includes sulfur, vitamins, trace elements. It defines several types of hair that grow on the human body. Long hair is the most robust and growing on the head, and these are the beard, mustache, genitals, armpits.

Bristly hair - a hair growing in the nose and ears, and eyebrows, eyelashes. Vellus hair grows on the skin of the arms, legs, torso and face.

Healthy hair elastic and have a high margin of safety. Healthy hair is easy to stretch and can withstand up to 200 g loads. Human hair is hygroscopic: they are easy to absorb moisture. They are resistant to acids, but very poorly responsive to alkali.

Most of the hair located on the roof of a human skull. Eyebrows on average contain about 600 hairs and eyelashes - 400.

If the operation of the hair is determined by their properties, the color depends on the correlation between the two species Melanin : eumelanin   and pheomelanin . These types of melanin granules of different shape: eumelanin granules have lengthened, and the form of granules pheomelanin oval or round. Consequently, eumelanin is called granular pigment, and pheomelanin - diffuse. Each hair contains two kinds of pigments in varying proportions. Consequently, people have three different hair colors: red, blondes and brunettes. But shades of hair color a lot more: they number up to 300.

Hair Options

It is important for the function of human hair. First of all, hair is an ornament, that is, perform an aesthetic function. They can either emphasize the dignity of the person, and to hide his shortcomings. However, not only the aesthetic function perform human hair. They help avoid both supercooling and overheating of the head. In hair creates a layer of air, which helps to keep the heat and cold. Vellus hairs that are located on the body are involved in the process of touch. The hair that grows in the nose and ears, helping to hold the dust. Eyelashes human help to protect the eye. Those hairs that are located under the armpits, can reduce the friction force. Consequently, a person commits any movement, and the skin is not damaged. Furthermore, in the hair may accumulate certain substances. This function successfully use them in forensic work.

In general, the function of mammalian hair reduced to ensure insulation protection of the skin against external impacts, providing color (in animals it is a masking and attractiveness). In addition, the animals have special hairs that allow them to orient in space, that is, they are responsible for sensitivity. But in the evolution of human hair partially lost these functions.