Closer Hair Check

Hair stylists and technicians examine the whole head of hair as part of their everyday practice. Matters to note include racial type, hair length and hair thickness, and if there is evidence of weathering, of previous cosmetic treatments such as perming and tinting and of accumulated hair spray.
A closer examination of the roots under a good light usually indicates the real state of the hair. The first centimetre or two of growth may look very different from the rest. This could indicate a change in the treatment that the hair has received, perhaps to a persistently harsh regime.

Next comes a look at the individual hair shafts with the naked eye. This may not reveal much, unless there is unusually serious damage. In very long hair that has weathered, the end may look a different color from the rest, or perhaps less glossy. This is almost certainly the onset of split ends.

Under the microscope, however, a very different picture may emerge. Hair scientists use both ordinary microscopes and electron microscopes to examine hair in the laboratory. These allow them to understand what happens to hair when it is heated, permed, tinted and so forth. You will find examples of what can be seen under both kinds of microscope throughout this book.

Loose Hair

Many people worry because they often find loose hairs on their clothes, or after shampooing, and they become terrified in case they may lose some or most of their hair.

If you pull the hair lightly with your hand, you may well find that a few hairs do come out. These are almost certainly hairs that are ready to fall anyway - telogen hairs. You can confirm this by looking at the roots in a good light. A telogen follicle root is a little hard, white bead. Brushed-out hairs all have this kind of root.

On the other hand, the root of a hair that is pulled out is fat, soft to the touch and sticky - it will stick to your hand, because it still carries fluid from the follicle. And pulling it out hurts! This is an anagen hair, one which was not ready to be shed.

Hair Check

From time to time doctors, scientists, hair stylists and technicians are all asked, for different reasons, to examine someone's hair. All of them need to know the right methods to use, and to understand the hair growth cycle and the cosmetic treatments and weathering processes that affect the hair's appearance

Hairlines

Forehead hairlines are determined genetically. The hairline that you were born with may well be the one you ultimately have in your adult life. Nearly all women keep their frontal line unchanged from childhood to old age, although some women's hairlines may seem to recede because their hair gets thinner. About half of all men may expect the hairline to recede to some extent, however.

Hair Stream

A hair does not grow straight up out of the skin, but leaves the follicle at a definite and predetermined angle. This angle determines the direction along which the hair will lie, and determines the patterns or streams that the hairs make on the head. Often the streams spiral outwards from a central point (or points) on the crown of the head. Usually these spirals, or 'whorls', run in a clockwise direction.

The classical 'cowlick', seen in around 7% of children, is due to a particular hair stream on the forehead. Unruly hair in children may be the result of scalp hair patterning. Another possible reason is an unusual structure of the hair shaft.

Hair Growth in Puberty

At puberty the immature vellus-like hairs on our bodies can change to terminal hairs. This change results from the dramatic rise in androgen levels at that time. It is especially noticeable in young men. Young women who suffer from the condition of anorexia nervosa, however, stop having periods and produce very little oestrogen: their natural androgens tend to thicken their fine vellus-like hairs in the same way.

The effects of androgens continue long after puberty. Some areas of the skin respond to these hormones more vigorously than others do, and at different times of life. Pubic and armpit hair begins to grow at or soon after puberty. Most men's beards do not grow strongly until the owners reach their thirties. The growth of chest hair reaches a peak even later, and hair in the nose and ears grows most in late middle age.

Scalp Hair

The hair of the scalp is, however, most sensitive to the effects of male hormones (androgens), which are in the blood of people of both sexes (only in different proportions in men and women). Androgens are the most important factor regulating hair growth, and also the thickness of the hair shaft. Female hormones (oestrogens), which both sexes have too, slow down hair growth during the growing period but also make that period longer. Many women notice a difference in their hair growth during pregnancy. At this time women have vast amounts of oestrogen in their blood, far outweighing their male hormones. It is the balance between the male and female hormones which decides the growth of the hair.

Vitamins for hair growth

Some Vitamens may be particularly important for hair growth. For example, some people who lack zinc in their diet produce only fine, sparse hairs and even lose their hair. Vitamin B, also known as panthenol, plays a part in hair growth. It also improves the physical properties (elasticity, strength and gloss) of the hair shaft.

The hair cycle for each individual hair is influenced by the levels of various hormones in the blood. Thyroid hormone speeds up growth in resting hair follicles. Steroids taken by mouth slow it down, though steroids inhaled for the treatment of asthma do not affect hair growth.

Hair Growth | What controls Hair Growth

No one can answer this question with certainty. What we do know is that it takes a lot to stop hair growing!
General health and nutritional factors are increasingly believed to be important for healthy hair growth. We do know that serious anaemia affects hair growth. So too does starvation: people who go on a crash diet may start to lose their hair some six to ten weeks later. Many alcoholics have poor hair growth or even hair loss because their way of life tends to lead to malnutrition.

Hair Length

How long anagen lasts is determined genetically, and varies between the sexes and from one person to another. It is the length of this time that decides how long the hair will grow before it falls out. Anagen lasts between three and seven years in most people.

• As we have seen, a hair grows at a rate of about 1centimetre a month.

• After one year it will be 12 cm long. After five years it will be 60 cm long.

• Waist-length hair is 80-90 cm long, and will have taken about seven years to grow.

• Shoulder-length hair will have taken only about three years. Thus only people with long anagen times can expect to grow their hair down to the waist.

As people grow older the period of anagen shortens. For example, the hair of someone with a five-year anagen can grow to a length of 60 cm before it enters the shedding phase. If their anagen period drops to three years as they age, their hair will then grow only to shoulder length before it falls out or is brushed out. So when a scanty-haired elderly lady boasts that when she was a girl she could sit on her hair, she may very well be telling you the truth!

Telogen (The Shedding Phase)

The telogen phase lasts for three or four months. This is the time at which a new hair begins to grow from the hair follicle. As it grows upwards the old hair will be shed naturally or may be pulled out, which happens easily and painlessly with telogen hairs. These are the hairs that come out when you shampoo or brush your hair.
Shedding is part of the normal process of the replacement of old hair with new. At any one time, around one in ten of the follicles on an individual's head are in the shedding phase.

The new hair emerges from the same opening at the surface of the skin as the old one, and the hair cycle begins again.

Catagen (The Intermediate Phase)

The anagen phase is followed by a short resting phase. This catagen phase lasts for between two and four weeks in the human scalp. No pigment is made during that time, and the follicle stops producing hair. The base of the follicle moves upwards towards the surface of the skin.

Anagen (The Growing Phase)

The anagen phase of a new hair starts at the moment it begins to grow. At that time there is very active growth in the hair bulb. This usually lasts for some years, generally between three and seven, without interruption. Since human hairs grow at a rate of roughly 1 centimetre a month, hairs can grow to a length of a metre or so.
As we have seen, hair may grow more quickly in winter than in summer. Hair growth varies with the season as a result of a change in the difference between hair follicles in the growing and shedding phases.

Pigment (melanin) is made in the hair bulb throughout this phase of the hair cycle. Less pigment is made in the hair of older people. This is why white hairs start to appear, even though the hair itself may still be growing strongly.

In some older people the hair cycle becomes shorter, the follicles gradually give up producing long, strong hair, and the hairs become thinner and shorter. The result may be a general thinning of the hair, or even a degree of baldness

Stages of the Hair Cycle

Between starting to grow and falling out years later, each hair passes through three distinct stages. These are so important that they have been given special names:

• Anagen (the growing phase)

• Catagen (the intermediate phase)

• Telogen (the shedding phase)

We shall look at these three stages in turn.

The Hair Growth Cycle

Each individual hair is formed inside a hair bulb deep in a hair follicle. The follicle is a tiny but powerful factory, which throughout many people's lifetime hardly ever stops working. From a baby's birth for many decades, as much as a century in some people, the follicle continues to produce hairs. Each hair grows for many years: during this time it will be shampooed, conditioned, cut, blown dry, exposed to sun and wind, colored or bleached or permed. None of these treatments affects the growth of the hair in the hair bulb, even though some may seriously damage the hair shaft. Finally the hair spontaneously falls out. The follicle rests for a little while, and then starts to produce yet another new hair. This is the hair cycle.

You need to know about the hair cycle in order to understand many of the problems people have with their hair. These can range from the sudden appearance of hairless patches to complete baldness in men, and sometimes in women too.

Hair Dimensions

Hair Dimensions vary from person to person.People describe their hair as being thick or thin, coarse or fine. What they are usually talking about is the amount of coverage their hair gives to the head. This coverage depends on two things: how many hairs there are, and the thickness (diameter) of each hair shaft.

People vary a lot in how many hairs they have, and also in how closely together they grow. The 'average' person has around 100,000 hairs, but people with very dense hair may have as many as 150,000.

The Hair Shaft Diameter varies too. Hair Shaft Diameter is usually around 57-90 µm in Europeans. This is much less than in Asians, in whom it can be 120 µm. (These are general figures, representing a wide range of values.)
Hair that is both dense and thick looks completely different from that of someone who has fewer and finer hairs