The Ultimate Hair Dictionary August 01, 2017 15:00
What is our hair made of? Why do some people have dandruff? How long can people grow their hair? Check our hair dictionary for interesting information on hair and learn some hairy definitions in the process
Pigments in the hair follicles give our hair its natural colour. They are produced inside specialised cells and from there travel through tiny channels to the keratinocytes, which we see has our unique hair colour. In general, dark-haired people have a higher concentration of pigments in their hair than blondes.
The cuticle layer forms the outermost lining of the hair. The condition of this outer layer indicates the state of the hair’s health. In the optimal case, flat scales are tiled smoothly around the cortex and protect the inside of the hair shaft against damaging influences from the outside. Intact cuticle layers around the hair form a smooth, light-reflecting structure.
In contrast, the cuticle layer of stressed hair (due to bleaching, perming and frequent hot blow-drying) is disorganised and rough. As a result, the entire head of hair looks brittle, dull and shaggy. Intensive hair treatments can restore the smooth structure of the cuticle layer.
Individual hairs go through a sequence of developmental phases. Most of the hair on your head (about 80%) are in the growth phase. During this time new hair root is generated and the hair grows. This phase lasts between two and seven years. and then from there a two to three week long transitional period follows. At this point the cell production in the follicle stops temporarily, the follicle constricts and the hair falls out. Approximately one per cent of the follicles are in this transitional phase. Lastly there is the resting phase where the hair follicle regenerates, the cells start to divide again and a new hair starts to form.
Dandruff shows up when the scalp sheds dead skin cells prematurely and in excessive numbers. This can happen whether the scalp is dry or oily. Different conditions may cause dandruff, such as stress, improper nutrition, hormonal changes as well as dry heated air, frequent blow-drying or aggressive shampoos. Remedies are anti-dandruff shampoos with active ingredients like Octopirox or zinc pyrithione.
The hair follicle is a slanted indentation in the scalp, in which the individual hair is anchored. The hair shafts form inside these follicles. Sebaceous glands end in the upper part of the follicles to provide the hair and scalp with oil.
Grey hair is not really grey but rather a mixture of colourless and pigmented hair. The mixture appears grey. Hair turns white when the pigment cells reduce their melanin synthesis. In some people, this process starts very early and very late in others. Genetic factors determine when the first white hairs appear.
Hair grows 0.3 to 0.45 mm per day or 1 to 1.2 cm per months. It is practically impossible to influence the hair growth from the outside. The maximum hair length ranges between 40 and 80 cm.
Losing 30 to 100 hairs per day is normal. Several conditions can result in losing more than the maximum of 100 hairs per day. In about 95 % of all cases of both male and female hair loss, genetic factors are to blame. Due to the overproduction of male hormones (androgens), the blood supply to the hair follicles is reduced and in turn, the hair is no longer tightly anchored in the scalp.
Keratin gives structure to hair and nails and it is a very elastic protein.
Protein gives the hair its strength and accounts for 80% of its structure
Life Span of Hair
On average, a hair remains in the scalp for six to eight years before it falls out. The individual life span depends on genetic factors. In cases of severe hair loss, the life span of hair may be reduced to three or four years.
The skin pigment melanin also occurs inside the keratin fibres of the hair. The amount of melanin determines how light or dark the hair is. As people age, the melanin production slows down and the hair turns gray or white. There are two types of melanin, the larger brownish black eumelanin pigments and considerably smaller reddish yellow pheomelanin pigments. All existing human hair colors are composed of these two pigment types.
The hair contains naturally occurring moisture which creates softness and suppleness. When the cuticle is damages it is difficult to maintain moisture levels and the use of heat styling tools increases this depletion
Our genetic make-up decides whether we have thick or thin hair. Hair with a diameter of 0.04 to 0.06 mm as fine, hair with a diameter between 0.06 and 0.08 mm as medium, and hair with a diameter between 0.08 and 0.1 mm as coarse.
The skin on the scalp resembles the rest of the skin and it is equally sensitive. Despite the hair, the scalp can get sunburned. Cold, heat and other conditions may dry out the scalp and cause itching and/or dandruff. For a variety of reasons, the sebaceous glands in the scalp may produce excessive amounts of sebum and lead to a oily scalp.
Sebaceous glands exist almost everywhere in the skin, including the scalp. These glands produce the oil, which protects the scalp and hair from drying out. The sebum synthesis may be out of kilter ever now and then due to genetic predisposition, stress or hormonal changes. This may result in a oily scalp and oily hair or to a very dry scalp. Either condition may lead to bothersome scalp conditions with itching, redness or dandruff.
Only a pair of scissors can remedy severe cases of split ends
Long hair frequently shows split ends. In most instances, this is caused by mechanical stress like combing, brushing or bouncing off the shoulder. Frequent colouring, bleaching, perming or using heated styling tools may also lead to split ends. Split-end fluids can be used to coat the split ends with a whisper-thin silicone film to improve the appearance of the hair at least for a while. Otherwise, a haircut is the only effective solution.
A single hair is able to hold at least 100 g weight without breakage. That brings the combined bearing capacity of all hairs on the average scalp to at least ten tons.
Structure - The Way Hair is Built
Hair consists to roughly 80 % of keratin (protein), 10 to 15 % is water and the remaining 5 to 10 % are pigments, minerals and lipids. The cuticle layer forms the outer layer of every hair. The cuticle layer envelops the inner part of the hair shaft called the hair cortex. The cortex comprises about 80 % of the hair mass. Colouring, bleaching or perming takes place inside the hair cortex.
How many hairs a person has on average depends on the hair colour. With 150,000 hairs blondes have the most hairs. Black-haired people come in second with about 110,000 hairs, followed by brunettes with 100,000 hairs and redheads with 80,000 hairs.