There many factors influencing the way our hair looks, among them regular taking care of our hair and conditioning. Hairs are considered to be skin appendages, as well as nails, sebaceous and sweat glands. A grown up man has got approximately 5 million hairs altogether. There are about 100 000 hairs of the scalp and their thickness goes from 40 to 800 per cm2. There are different types of hair, i.e.: lanugo, or downy hair, and the hair of a grown up person.
How is our hair built?
The hair root of an individual hair forms a tiny but long tunnel (called a follicle) which reaches into the lower layers of the skin. The hair is divided into a shaft: the portion growing above the skin and the hair roots anchored in inside the follicle. At the end of the tiny tunnel, there is a hair papilla. The papilla is the centre of growth for the hair; it is where nutrients are taken up from the blood. Another part of the hair is its hair bulb which contains pigments. The content of the tubular hair determines its colour. The surface of the tubular structure is scale-like, covered with tiny plates. Each hair has got three layers: interior, cortical and hair shell.
Melanocyte, a pigment-producing cell in the hair determines their colour. The pigment that melanocytes make is called melanin. The major determinant of colour is not the number but rather the activity of the melanocytes. Melanin production takes place in unique organelles (tiny structures within the cell) known as melanosomes. Darkly pigmented skin, hair and eyes have melanosomes that contain more melananin.
The hair is built in a tubular way and consists primarily of a substance called keratin. This is scleroproteid with the variety of amino acids which form polypeptide chains. In keratin there are such amino acids as: arginine, cystine, glycine, tyrosine, fenyloalanine, lysine, and other amino acids.
How does the hair grow?
Hair does not contain nerves or blood, but instead is rooted in living skin, which is how a uniform structure is formed.
Hair does not grow continuously. There are three phases of hair life. The transitory phase which lasts approximately 2 to 4 weeks, and a hair turns loose from the papilla and moves slowly upward in the hair follicle. During the resting phase, which lasts from 2 to 4 months, hair has reached the sebaceous gland and is ready to fall out, thus making room for his successor. The growth phase is the phase during which hair sits firmly in the hair papilla and, dependent upon genetic factors, matures during its 2 to 7 years of growth, becoming longer and longer. The majority of hair on a healthy grown up person’s scalp is in the growth phase while only 10% of hair is in the resting phase.
On the scalp 85% of hair should be in the growth phase.
The lifespan of hair on a head may vary from four to even twenty five years. The hair may be 2 meters long then. This hair is also the quickest growing hair of a human body. The hair grows 0.35mm a day on average. The phase of growth of a man’s beard lasts approximately 40 weeks. The cycle of eyelashes’ growth varies from 3 to 5 months. For babies, in their first half a year of life, the resting phase of hair cycle is much longer than for adults. Downy hairs are only a few centimetres long before they start falling out, which is quite normal. The physiological norm for the hair loss of an average person is about 100 hairs per twenty-four hours. If we lose more, this may be a sign of some malfunctioning of our body. The state of hair is important in diagnosis of many diseases.
What can influence the condition of our hair?
There are numerous important factors which influence the state of our hair, its thickness, the right growth, as well as its physiological composition and biochemical.
Nourishing elements
These are very important. The way a person’s hair looks provides strong evidence on his malnutrition or/and under nourishment. It has been proved that after two weeks of following a non-protein diet, there are signs of disappearing of hair bulbs and thinning of the hair follicles.
Amino acids – are necessary to make the proper hair growth possible. While doing some experiments on animals, it has been proved that the most dangerous is the deficiency of cystine. In turn, the deficiency of metionin causes dryness and brittleness of hair. The deficiency of tryptophan causes alopecia, while the deficiency of cystein makes the hair lose the gloss.
Carbohydrates – give hair the proper amount of energy which is important for hair metabolism. It is because hair in follicles is one of the fastest growing parts of human body.
Vitamins – Hair is very sensitive to the deficits of all vitamins but in particular to the deficiency of Vitamin A. Avitaminosis / hypovitaminosis A may cause particular ocular and dermal changes. The most important ocular changes are: the night blindness and changes of cornea. As for the dermal changes we may find one called hyperkeratosis. The hair of a sick person becomes weak, dry and brittle.
Microelements – The deficiency of microelements has got a great impact on the hair growth. The most important microelements are: zinc, iron and copper.
- The deficiency of zinc may cause, among many others symptoms, hyperkeratosis of skin and hair loss. The 24-hour requirement for zinc is 2mg. This element is very difficult to assimilate. This means that only 1/6 part of zinc brought with food gets assimilated by our body. Zinc also is easily extracted with faeces, urine and sweat. Therefore even if the amount of zinc (10-15mg) in our diet is sufficient in the majority of cases, sometimes there are cases of deficiency of this element in our country.
- The deficiency of copper may lead to some structural changes and discolouration. Pathological changes in hairs in so-called Menkes complex, which is genetically conditioned defect of transportation of copper in the alimentary tract, are good examples of such changes.
- The deficiency of iron may cause the alopecia. The example of such a state is sideropenia, which causes an extensive alopecia of women.
In many cases microelements get inside hair through the blood, firstly into its bulb and then into its root and further. Arsenic and selenium are examples of such microelements. Other elements can also get inside hair through the keratin, for example lead. Lead remains mainly on the outer parts of hair, though. Intoxication with lead, arsenic and selenium may also cause alopecia.
Hormonal agents
They have very a strong impact on hair growth. The example of such may be the activity of testosterone, one of the androgenic hormones. Androgens stimulate the growth of hair but the head whereas on the scalp, androgens remain responsible for the male type of alopecia. Alopecia is genetically conditioned. When a man reaches his sexual maturity, testosterone causes thinning of hair on his head in specific places. Hair bulb starts disappearing.
Stress
It has got an enormous effect on the way our hair look. It may cause the extensiveness of hair loss and development of alopecia.
Natural adornment
Hair protects from the destructive thermal factors and UVA/UVB. However, its active role is not very important, which is quite the reverse to the psychosocial importance of hair in human life. It is because hair is the natural adornment of man. Its appearance has got a huge impact not only on our general feeling but also on our relations with other people.
We need to remember that taking care of our hair by using chemical preparation, we should also provide our body with appropriate nutrition and balanced diet because this is the best way we can take care of our health.
If our hair tends to fall out, the reasons for this should be traced in the dysfunction of inner organs, e.g. any kind of hormonal disorder or food deficiency. In some cases, after consulting a doctor first, we can use special vitamin or microelement preparation as a supplement of our diet.
It is very important to notice that examining our hair, in many cases may help us to put the diagnosis about the general health condition of our body.
Examining of hair
Owing to different scientific methods we are able to find out the degree of hair loss, as well as to check the hair shaft under the electron or light microscope and to examine the state of a hair root, which enables to calculate the percentage of hair growth, involution and rest phases.
Absorptive spectrophotometry defines the amount of microelements (e.g. Mg, Zn, Fe) in human hair which allows to discover the deficiency of metals necessary for the hair growth and defines the level of the body poisoning, for instance by lead. WHO and International Agency for the Protection of Environment have chosen human hair as a distinctive element to evaluate the influence of toxic substances on living organisms.
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