Good looking hair is essentially healthy, shiny and clean. But our hair is constantly exposed to the aggressions of the environment and age and these tend to have a negative influence on its appearance—so most of the hair-care products we use, aim at reducing these effects thereby making the hair look attractive as our crowning glory.
Structure of Hair
Hair is all protein : The part of the hair we see is dead; the actual living part is very small and is at the root in a part known as the papilla. In the papilla, cells multiply and produce a protein called hard keratin—this is responsible for the hardness of the hair.
The part of the hair which is within the skin, is enclosed by a sleeve of tissue called the follicle. Next to each follicle is a sebaceous gland, the oil producing factory of the skin. This oil forms a natural protective film over the length of hair, keeping it soft, shiny and supple.
Each hair is made up of three layers—the cuticle or the outer most layer which has tiny overlapping transparent scales. When the scales lie flat against each other, the hair appears shiny, but when the scales are lifted, hair seems rough and dull. Conditioning rinses help to keep the scales positioned correctly, giving it a smooth and shiny appearance.
The cuticle of the hair is selectively porous. This porosity varies along the length of the hair, the youngest bit near the scalp being the least porous. Also oily hair is less porous than dry hair. The porous nature of hair allows for the penetration of chemicals. The agents used in bleaches, tints and perms capitalise on this nature of the hair—the chemicals used are quickly absorbed and bring about the necessary changes in colour and curliness.
The cortex or middle layer of hair contains the colour pigment granules. The colour of hair depends on the number, size and distribution of the pigment granules in the cortex and also on the nature of pigment present. Colourants and bleaches work by penetrating the cuticle so that the colour is added to or subtracted from the cortex. The innermost layer is the medulla; it is absent in very fine hair.
Shape And Colour of Hair
Straight hair or curly hair?
Curly hair has a flattened cross-section while straight hair has a circular one. The basic hair form is controlled by a number of genes—but this hair form is readily altered by chemicals present in perming and straightening lotions.
Thick hair or fine hair?
Except for palms, soles and lips, hair is present all over the body. In some areas it is long, thick and dark—this is the terminal hair seen on the scalp, on the face of adult men and in the axilla and pubic region of adults; some terminal hair are also present on the arms, legs and body. The hair on the rest of the skin is short, fine, light, and inconspicuous—this type of hair is called the vellus hair.
Sometimes hair which is normally supposed to be fine and inconspicuous becomes visible; for instance terminal hair appears on the face of women in a condition called hirsutism. On the other hand, sometimes terminal hair gets converted into fine vellus hair—this happens in the all familiar baldness seen in men.
Colour of your hair
The colour of your hair depends on the number, size and distribution of pigment granules in the cortex and the nature of the pigment present. The granules in black, blonde and red hair are different chemically—the brown black hair is due to melanin, the blonde hair contains phaeomelanin and red hair erythromelanin.
It is thought that a number of genes influence of the colour of the hair—some of these genes also influence other inherited characteristics as well—the association between hair colour and hair form is well established. There is also an obvious association between hair colour and the colour of the eyes, the colour of the skin and the presence of freckles.
Though, the basic colour of your hair is determined by your genes, this colour is readily altered by colouring agents. It can be lightened using bleaches, highlighted by a variety of agents and darkened by several types of natural and synthetic hairdyes.
Hair Growth
How fast does hair grow?
The rate of hair growth varies considerably but on an average it is one cm per month. The growth is greater in summer than in winter. It is maximum in the ages between 15-30 years. Cutting or shaving does not make hair grow faster. Neither does trimming affect the growth rate in any way, though trimming does make your hair look good by eliminating the straggly ends.
Each hair undergoes cyclic activity in three phases—the growth phase or anagen lasts for 3-4 years; following anagen is a short period of transition or catagen, following which is the phase of telogen or resting. During the resting phase (2-3 months) the hair becomes detached from its root and falls out, as a new growing hair replaces it in the follicle.
At a given time, 10-15% of the scalp hair are in an inactive phase, ready to fall out, while the remaining are in various stages of growth. A loss of up to 100 hairs per day is normal and is something you should not worry about as most of the lost hair would be replaced. With age, however, the rate of replacement slows down; so as you grow older, there is a natural tendency of some amount of sparseness of your scalp hair.
What controls the growth of hair?
Family background and racial factors are very important for the quality as well as the quantity of hair. Good quality long hair runs in families, and so does the all familiar male type of baldness.
Nutrition: Hair like any other aspect of your looks is best improved by treating your system well. A good balanced diet is what is really required. An inadequate diet disturbs the structure, the growth and the colour of hair. When there is a total deficiency of protein, the hair becomes sparse, fine, brittle, dry and light coloured. The severe hair loss seen after crash diets is primarily due to protein deficiency. High protein diets especially those containing gelatin and cysteine have been seen to have increased the reats of hair growth. Deficiency of pantothenic acid leads to premature graying of hair in animals. Lack of essential fatty acids also causes hair to fall. Iron deficiency, especially in women, has been associated with hair loss, while iron supplementation hastens the growth of hair. Zinc deficiency also leads to hair fall. So an ideal diet for hair growth should contain adequate amounts of iron, protein and fatty acids.
Age : With progressively increasing age, there is a decrease in hair growth. The replacement of shed hair is also incomplete and this results in sparsity of hair. In men, there is a recession of the hairline and sometimes definite areas of baldness appear. This baldness is dependent on the male sex hormones—the androgens. Rarely this hormone-mediated baldness is seen in women too.
Hormones: A number of other hormonal disorders can cause hair loss—thyroid disorders being the commonest. Though during pregnancy, hair loss slows down or may even stop altogether, excessive hair fall commonly occurs three to four months after delivery. Contraceptive pills also cause excessive hair loss and this stops when the pill is discontinued.
