About Hair
Hair is far more complex than it appears on the surface. We all know that it not only plays a vital role in
the appearance of both men and women. Hair is much more complicated than it appears. It helps transmit sensory
information and creates gender identity.
Hair is important to the appearance of men and women. There is hair on all the major visible surfaces of the body. It is also the only body structure that is completely renewable without scarring. This article explains what exactly hair is and how it works.
Hair is simple in structure, but has important functions in social functioning. Hair is made of a tough protein called keratin. A hair follicle anchors each hair into the skin. The hair bulb forms the base of the hair follicle. In the hair bulb, living cells divide and grow to build the hair shaft. Blood vessels nourish the cells in the hair bulb, and deliver hormones that modify hair growth and structure at different times of life.
Q: What is hair?
A: On our heads, we have hundreds of thousands of follicles, pore-like structures within the scalp that produce hair. Each follicle produces many hairs throughout our lifetime.
Live hair cells are generated inside the follicle by the papilla. As the new cells grow, the older cells die and are forced along the follicle towards the scalp. The dead cells are compressed to form a protein called keratin. The hair shaft that we see is the keratin emerging from the scalp. Finger-nails are made of keratin, too.
Each hair consists of keratin, small amounts of water and a binding agent, which holds the keratin and water together.
Q: What is hair?
A: On our heads, we have hundreds of thousands of follicles, pore-like structures within the scalp that produce hair. Each follicle produces many hairs throughout our lifetime.
Live hair cells are generated inside the follicle by the papilla. As the new cells grow, the older cells die and are forced along the follicle towards the scalp. The dead cells are compressed to form a protein called keratin. The hair shaft that we see is the keratin emerging from the scalp. Finger-nails are made of keratin, too.
Q: What is Hair Anatomy?
A: Hair has two separate structures - the follicle in the skin and the shaft we see.
Follicle - The follicle is a stocking-like structure that contains several layers with different jobs. At the base of the follicle is a projection formed like sticking a finger in the bottom of a stocking and pushing it in a small amount. This projection is called a papilla and it contains capillaries, or tiny blood vessels, that feed the cells.
The living part of the hair is bottom part of the stocking surrounding the papilla called the bulb. This bottom part is the only part fed by the capillaries. The cells in the bulb divide every 23 to 72 hours, faster than any other cells in the body.
The follicle is surrounded by two sheaths - an inner and outer sheath.
These sheaths protect and mold the growing hair shaft. The inner sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland, and sometimes an apocrine (scent) gland. The outer sheath continues all the way up to the gland. A muscle called an erector pili muscle attaches below the gland to a fibrous layer around the outer sheath. When this muscle contracts, it causes the hair to stand up.
The sebaceous gland is important because it produces sebum which is a natural conditioner. More sebum is produced after puberty. The sebum production decreases in women throughout their lives. The production also decreases in men, but not as much as in women.
Shaft - The hair shaft is made up of dead, hard protein called keratin in three layers. The inner layer is called the medulla and may not be present. The next layer is the cortex and the outer layer is the cuticle. The cortex makes up the majority of the hair shaft. The cuticle is formed by tightly packed scales in an overlapping structure similar to roof shingles.
Most hair conditioning products attempt to affect the cuticle. There are pigment cells that are distributed throughout the cortex and medulla giving the hair its characteristic color.
Q: What are the Hair Follicles?
A: Hair has two distinct structures - first, the follicle itself, which resides in the skin, and second, the shaft, which is what, is visible above the scalp.
The hair follicle is a tunnel-like segment of the epidermis that extends down into the dermis. The structure contains several layers that all have separate functions. At the base of the follicle is the papilla, which contains capillaries, or tiny blood vessels that nourish the cells.
The living part of the hair is the very bottom part surrounding the papilla, called the bulb. The cells of the bulb divide every 23 to 72 hours, remarkably faster than any other cell in the body.
Two sheaths, an inner and outer sheath, surround the follicle. These structures protect and form the growing hair shaft. The inner sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland, and sometimes an apocrine (scent) gland.
The outer sheath continues all the way up to the gland. A muscle called an erector pili muscle attaches below the gland to a fibrous layer around the outer sheath. When this muscle contracts, it causes the hair to stand up which also causes the sebaceous gland to secrete oil.
The sebaceous gland is vital because it produces sebum, which conditions the hair and skin. After puberty our body produces more sebum but as we age we begin to make less sebum. Women have far less sebum production than men do as they age.
Q: What is hair Shaft?
A: The hair shaft is made of a hard protein called keratin and is made in three layers. This protein is actually dead, so the hair that you see is not a living structure. The inner layer is the medulla. The second layer is the cortex and the outer layer is the cuticle. The cortex makes up the majority of the hair shaft. The cuticle is a tightly formed structure made of shingle-like overlapping scales. It is both the cortex and the medulla that holds the hair's pigment, giving it its color.
Hair Growth Cycle
Q: What is hair Growth Cycle?
A: Human hair cycles through three stages:
Hair on the scalp grows about .3 to .4 mm/day or about 6 inches per year. Unlike other mammals, human hair growth and shedding is random and not seasonal or cyclical. At any given time, a random number of hairs will be in one of three stages of growth and shedding: anagen, catagen, and telogen.
Anagen
A: Human hair cycles through three stages:
Anagen is the active phase of the hair. The cells in the root of the hair are dividing rapidly. A new hair is formed and pushes the club hair (a hair that has stopped growing or is no longer in the anagen phase) up the follicle and eventually out.
During this phase the hair grows about 1 cm every 28 days. Scalp hair stays in this active phase of growth for two to six years.
Some people have difficulty growing their hair beyond a certain length because they have a short active phase of growth. On the other hand, people with very long hair have a long active phase of growth.
The hair on the arms, legs, eyelashes, and eyebrows have a very short active growth phase of about 30 to 45 days, explaining why they are so much shorter than scalp hair.
Catagen
The catagen phase is a transitional stage and about 3% of all hairs are in this phase at any time. This phase lasts for about two to three weeks. Growth stops and the outer root sheath shrink and attaches to the root of the hair. This is the formation of what is known as a club hair.
Telogen
Telogen is the resting phase and usually accounts for 6% to 8% of all hairs. This phase lasts for about 100 days for hairs on
the scalp and longer for hairs on the eyebrow, eyelash, arm, and leg. During this phase, the hair follicle is
completely at rest and the club hair is completely formed. Pulling out a hair in this phase will reveal a solid,
hard, dry, white material at the root. About 25 to 100 telogen hairs are shed normally each day.
Q: How hair grows?
A: Hair grows, stops growing, falls out and starts again continually throughout our lives. If something happens to stop this process of renewal, the hair will not replace itself and we will go bald.
Our hair can grow for between one and seven years. On average, it will grow to a length of between 28 to 36 inches if it is not cut. Each hair we produce has its own growth cycle and, because each hair reaches a different stage of the cycle at a different time, our hair is continuously renewed and replaced.
Q: Does hair grow after death?
A: No, definitely not. It may appear to grow but in fact any change in length is due to degradation of the flesh to expose extra hair length that previously existed under the skin (the same goes for finger nails). Hair does get lighter after death though; this is due to oxidation of the melanin pigments.
Q: Does shaving, plucking or cutting cause hair to grow faster and coarser?
A: No, only hormones can control where, when and how hair grows (perhaps with the exception of surgery). The idea that short hair grows faster is to do with our perception of the change in length. Hair that began at 1cm long and grew 1cm in a month doubles in length; this appears to be a drastic change and is perceived as fast growth. Whereas hair that was 30cm long will not appear very different from hair that is 31cm long a month later and is therefore perceived to have grown more slowly.
Structure of hair
Q: What is the structure of hair?
A: Hair is made up of several layers:
Cuticle
The outer, protective coating of the hair is formed from overlapping scales and can be several layers thick. These scales are what make the hair flexible. The outer coating is translucent, which allows the color of the hair (from the cortex) to be seen. You can make the scales 'open up' to allow chemicals and other substances to penetrate the hair.
Cortex
The main bulk of the hair consists of long fibres, twisted together to form a rope. This is the cortex. At the centre of the finest threads of the cortex are three spiral, spring-like chains that are bonded together. It is these chains that give hair its ability to stretch and allow us to direct the hair into different styles.
The chains (polypeptide chains) are held together by three types of bond:
• hydrogen
• salt
• di-sulphide or sulphur
The di-sulphide bonds are the ones you need to break if you want to change the shape of the hair permanently but you need break only 25 to 30 percent of the bonds, i.e. less than one third.
The cortex determines the color of the hair. There are two pigments:
• melanin, which gives us brown and black
• pheomelanin, which gives us yellow and red
Medulla
This is the centre of the hair shaft. It does not play a part in hairdressing.
There are three types of human hair:
• Primary
• Secondary
• Tertiary
Primary
This hair is very fine. It helps us regulate the temperature of our bodies by aiding the evaporation of perspiration. It grows everywhere on our bodies except for our lips, the palms of our hands, soles of our feet and our eyelids.
Primary hair has a number of special features:
• It has no medulla;
• There is often no pigment, which is why primary hair can be hard to see;
• It is rarely more than half an inch long; and
• It has no arector pili muscle to hold it up.
Secondary
Secondary hair is short, bristly and coarse. Our eyelashes and eyebrows are secondary hair and it appears in the opening spaces of our ears and noses. It is sensitive to touch - think about how your eyelids blink to protect your eyes if you touch your eyelids. Our eyebrows also protect our eyes by preventing sweat, water and oil from running down the scalp.
You can identify secondary hair by a number of special features:
• it grows straight out from the skin;
• it has no arector pili muscle;
• it has a large medulla;
• it is often curved, such as eyelashes;
• it is usually between half an inch and an inch in length; and
• it usually increases in density as we get older.
Tertiary
This is the longer hair that grows on our scalps. In adults it appears under the arms and in the groin area and, in men, on the beard and moustache. Historically, tertiary hair was probably there to keep us warm and protect us from the sun. It has no particular function any more. Each tertiary hair has its own sebaceous gland to produce oil and an arector pili muscle to lift it up from the scalp.
Tertiary hair:
Grows from the follicle at an angle - this is what we see as the direction of growth. It varies across the head and can change direction creating natural partings or features like a double crown, it contains pigment - this gives hair its own distinct color; and it can be straight, curly or wavy.
Maintain healthy hair and scalp
Q: How to maintain healthy hair and scalp?
A: The main factors that determine the health of hair are:
Client's health
If our client is healthy, this will show in their skin and their hair. Good diet and exercise are essential for good health.
Diet
If our client is healthy, this will show in their skin and their hair. Good diet and exercise are essential for good health.
Fresh fruit and vegetables, sufficient protein and carbohydrates, and plenty of water will give a body all the nutrients it needs to stay healthy.
Environment
The condition of our client's hair will be influenced by their surroundings. Whether they live with soft or hard water will affect their hair and determine the cleansers and conditioners that should be used on it.
Clients who live near the sea will suffer the same effects on their hair as clients who live in areas with high pollution. Their hair will be coated with salt or impurities and will need to be washed and conditioned regularly, if not every day.
Damages of hair and scalp
Q: What are the Damages of hair and scalp?
A: The three main types of damage that you need to look for are:
• Physical
• Chemical
• Biological
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Physical damage:
As the hair grows, it gets older. The ends of hair that has grown below shoulder length, for example, are probably at least three years old. This hair will have been shampooed many hundreds of times, combed, brushed and exposed to all kinds of influences, many of which will have caused damage.
The most common ways that hair is damaged physically include:
Shampooing:
Over-frequent washing strips out the natural oils that lubricate and protect the hair.
Brushing:
harsh brushing strips the cuticle from the hair. Always brush with care using a good quality brush that is not damaged or broken.
Combing:
tugging the hair while it is wet, to remove tangles for example, over-stretches it and causes damage. Use a wide-toothed comb and gently untangle the hair from the ends downwards.
Rubber bands: elastic bands applied too tightly damage the cuticle layer and can cause the hair to break.
Roll ring:
over-stretching the hair around rollers can destroy the part of the cortex that allows the hair to be ‘elastic’. Never stretch the hair too far.
Heat:
holding a hair-dryer too close to the head or allowing too much heat to build up strips off the cuticle and exposes the cortex. The hair loses its natural moisture.
Electric tongs, etc:
possibly the most harmful form of heat because it is applied directly to the hair damaging the cuticle and exposing the cortex, which leads the hair to lose its natural moisture.
Chemical damage:
Every time a client applies chemicals to their hair, they damage it. Some chemicals are more damaging than others but they all have some effect. The most damaging chemicals are:
Cheap products: the use of inferior shampoos and styling products may, over time, make the hair difficult to manage.
Perm:
when hair is permed, the cuticle is raised so that the chemicals can penetrate, which changes the chemical make-up of the cortex. Perm chemicals, if improperly applied, can seriously damage and weaken the hair by altering its acidic balance.
Color:
misuse of color can damage and weaken the hair, particularly when the coloring process takes the hair out of its natural acidic state. In permanent coloring, the cuticle is raised to allow the chemicals to penetrate, which alters the chemical make-up of the cortex.
Bleach:
probably the most damaging process in hairdressing. The chemical strips the natural color from the hair and, at the same time, takes out much of the hair’s moisture. Once removed, this moisture can never be replaced.
Chlorine:
the same chemical that is used in swimming pools, chlorine is highly alkaline. It combines with the keratin in the hair to produce a ’glass-like’ effect. The process is particularly damaging for long hair.
Biological damage:
Some of the most common types of biological disorder are:
Folliculitis:
a bacterial infection of the hair follicles. You will see redness around the follicle and there may be small, yellow pustules in the centre of the follicle around the hair. If you identify this condition, you should not dress the client’s hair and you should advise them to seek medical attention.
Fragilitis crinium:
commonly known as ’split ends’. This happens when the cuticle of the hair dries and starts to fracture and split. You will see the splits at the ends of the hair and look for them particularly in long hair.
Split ends can be caused by inferior products or treating the hair harshly. There are some conditioning products you can use for a cosmetic repair but there is no cure except to cut the split ends away and strengthen the hair so that it is less likely to split again.
Impetigo:
this condition is a highly infectious, bacterial infection. Do not dress the client’s hair until they have had medical treatment. You can identify this condition by the small, red spots, which break to produce a thick, yellow crust. When they break, the spot join together to produce a large, crusted, infected area. If your client has this condition, you should advise them to seek immediate medical attention.
Pediculosis capitis or head lice:
This condition is extremely contagious and you should not dress the client’s hair. Lice are parasites that feed on the skin. The females lay their eggs, known as nits, on the hair. The eggs are attached to the hair with strong glue – you will be able to see them. There are a number of products you can recommend that the client can use at home to wash away the nits and clear the infestation.
Pityriasis capitis:
more commonly known as dandruff. We all shed dead skin cells from our scalps but when this is excessive it can become an unsightly problem. Dandruff can be caused by an infection or micro-organism or, sometimes, by a lack of sebum, either as the result of underproduction of natural oil or harsh treatment with inferior products. You can treat it with a combination of clinically tested medicines of Divya Sanjivni, cleanser, oils and medicines, moisturizing conditions, which soften and replace moisture in the scalp.
Psoriasis:
A skin condition that can appear anywhere on the body but you are most likely to find it behind the ears and around the hairline. In psoriasis, skin cells are reproduced at a faster rate than normal. This leads to scaly patches forming on the scalp which, if peeled away, leave sore areas of raw skin.
Sebaceous cysts:
you will see small hard lumps under the surface of the scalp where the sebaceous glands have become blocked with sebum. Sebaceous cysts can grow until they affect the appearance and growth of the hair but they are not infectious or contagious and will usually disappear on their own. If they do become unsightly, they can be easily removed.
Seborrhoea:
Is the name given to the condition that causes an unusually greasy or oily scalp. The oil or grease is excreted from the sebaceous glands in the scalp and can have a distinctive odor. The condition often appears in adolescence or can be related to a hormonal imbalance. It can also result from the over-use of cheap products. With severe cases, you can help your client by handling the hair carefully and recommending specialist shampoos or mild, quality products.
Tinea capitis:
Otherwise known as ringworm. This condition is very contagious and you should not treat the hair until the client has had medical attention. Ringworm is a fungal infection caused by a parasite and is easy to identify. The hair breaks close to the scalp and the skin forms red, ringed areas that are grey in the centre.
Trichorrexis nodosa:
sometimes known as ’beaded hair’. You will see swellings on the shaft of the hair and some hair may have broken at the point of the swellings. There is no complete remedy but you can help your client to manage the condition by strengthening the hair.
Warts:
These will not usually present you with any problems as you dress your client’s hair but it is worth taking care as some warts can be infections. Warts are caused by a virus infection in the skin. They can vary in size and shape and lots of people have them on their hands and feet and, sometimes, on the face.
Hair type
Q: How many hair type, texture and density are?
A: There are three types of hair:
• African Caribbean.
• Asian
• Caucasian (European)
African Caribbean
Usually very tightly curled and often very dark, African Caribbean hair is almost kidney shaped when seen in cross section.
African Caribbean hair is easily damaged. Take care when using treatments, particularly chemical treatments.
Asian
Asian hair is often straight and has a tendency to be lank. It varies in colour from very dark to medium brown and can be thick and very strong. In cross section, it is round.
If you cut Asian hair very short, it can stand straight out from the head.
Caucasian
Caucasian or European hair can be straight, wavy or curly. It varies in colour from very dark brown to light blonde. In cross section, European hair is oval.
Texture
Hair can be:
• Fine
• Medium
• coarse
When we refer to hair as being 'fine', 'medium' or 'coarse', we mean that each hair is fine, medium or coarse. The texture of hair is determined by its circumference and the condition of the cuticle. Fine hair has a small circumference and a closed cuticle, coarse hair has a much larger circumference and the cuticle will be more open. This will lead to the hair being more porous.
The texture of hair can determine what looks you are able to achieve. If hair is naturally coarse or if it appears to be coarse because the cuticle is open and damaged, you will not be able to successfully achieve a smooth look.
The texture of hair can vary significantly according to hair color and racial type (see also how hair grows).
Density
Density relates to the number of hairs on the head. A client with fine-textured hair may have many more hairs on their head than someone whose hair is coarse. The number of hairs on the scalp depends on many influences and varies enormously but average densities are believed to be:
• for natural blonde hair - 130,000
• for natural red hair - 80,000
• for natural brown hair - 100,000
• for natural black hair - 100,000
structure, features and function of the skin
A: The skin is one of the biggest organs on the body. It has two main layers -
the epidermis and the dermis.
Epidermis
Epidermis this is the outer surface of the skin that we can see and feel and where we find the hair follicles. It is made up of several layers that, together, form a protective outer sheath. This is protected by a mixture of water and oil (sebum) excreted from the scalp. The mixture is mildly acidic and contains 'friendly' bacteria.
The epidermis is constantly being worm away in a process called exfoliation.
Dead cells are shed from the skin and new, healthy cells take their place.
Dermis
This is the deep, inner layer of the skin that contains the blood and nerve
supply. On the scalp, the dermis contains the sebaceous glands that produce
sebum and the sudiferous glands that produce water. The oil and water mix
together to form a protective covering for the hair.
The dermis also contains nerve receptors that sense heat, cold and pain and
adipose tissue or fat cells.
A feature of skin the skin has a number of features. Most of these grow from the
epidermis down into the dermis. The main ones are:
• follicles - pore-like structures that produce hair
• dermal papilla - the origin of all cell growth and cell division
• sebaceous glands - secrete oil called sebum that protects us against bacteria,
lubricates and waterproofs the skin and, on the scalp, makes our hair soft, shiny and pliable
• sudoriferous (sweat) glands - excrete waste in the form of sweat, which
• evaporates to cool the body
• arrector pili muscles - attached to the hair follicles, these contract when we get cold. This
pulls the hair upright, giving us goose pimples and trapping
warm air around our body to help keep us warm.
There are four main functions of the skin:
• protection from strong sunlight and bacteria
• sensation through the nerves
• excretion of waste and oil to make us waterproof
• regulation of temperature by releasing sweat to cool us and trapping air
• around us to keep us warm
The natural pigment of the skin is the same as the pigment in the hair. It is
called melanin and is produced by cells called melanocytes.
Q: What exactly is hair made of and how does it grow?
A: your hair grows from follicles within the skin. The part of the hair inside the follicle (below the skin's surface) is known as the hair root, while the portion you see protruding from the head is the hair shaft. At the base of the hair root is the hair bulb where nutrients are received and new cells are formed.
Also within the hair follicle are the dermal papilla (a cone shaped protrustion at the base of the follicle which feeds blood - and therefore nutrients - to the hair bulb), the sebaceous gland (or oil gland) which lubricates and keeps the hair healthy and shiny, as well as the arrector pili, a tiny muscle anchored to the follicle. The arrector pili respond to stimulus (fear or cold) causing them to contract and make the hair stand up straight.
Taking nutrients from the dermal papilla, the hair bulb generates new hair cells. As these cells move
up through the hair root, they mature through a process called keratinization, fill with fibrous protein
and lose their nucleus. When the cell loses its nucleus it is no longer alive. By the time the hair
emerges from the skin it is merely fiber made of keratinized proteins.
The fibrous protein emerging from the hair follicle as the hair shaft has a specific construction. It forms a strand with three layers: an outer covering of overlapping keratin scales called the cuticle, a middle layer of keratinized protein fibers called the cortex, and, usually, a central 'core' of round cells called the medulla. A medulla is almost always found in coarse hair, and often is absent from naturally blonde hair and very fine hair.
Q: How fast does hair grow?
: The speed of hair growth is roughly 1.25 centimeters or 0.5 inches per month, being about 15 centimeters or 6 inches per year. With age the speed of hair growth might slow down to as little as 0.25 cm or 0.1 inch a month.
Cell division is responsible for the hair growth cycle. The new cells push the hair forward to make it longer, so the new hair is added at the root. There are about 100.000 hairs on a healthy scalp of hair. Each of these hairs will, in normal healthy conditions, last for one up to six years.
People lose about 50 to 60 hairs per day, in normal conditions. The fallen hairs are replaced by new hair. Baldness occurs when new hairs are not being produced anymore.
During its life a hair goes through three phases of growth: the anagen, the telogen and the catagen. The anagen is the first phase with new hair growing in the hair bulb. The catagen is the following phase when hair stops growing because the cell division stopped. The telogen is the final phase. New hair starts growing in the papilla and finally the old hair falls out.
Hair grows at about the same speed all over your head. There is no perceptible difference between the fringe, nape, crown...
You might think that fringes (bangs) grow faster than hair on other parts of your head, but that's simply an illusion. Many cut the fringe just above the eyebrows and because of this the slightest hair growth will be visible. Wearing a turtleneck will also make your hair look longer and maybe make you think that your hair grows faster. Again an illusion has been created here because of the straight line of the turtleneck.
Hair Diseases & Conditions
Q: How many types of Hair Diseases & Conditions?
A. Diseases of the hair, far from being a popular topic of conversation, are somewhat neglected, compared to the excessive amount of research and literature dedicated to many other equally undesirable conditions, leaving sufferers uninformed and bemused about what steps to take to help eradicate the problem.
Our hair, like our eyes and our smile, is one of the most first features people notice about each other, which helps us to form those valuable first impressions about other people.
Having hair which is full of life, vitality and health is therefore an attribute desired by most, and one which is heavily hampered by hair and scalp diseases which cause hair to become dry, brittle and lusterless.
Because of the unhealthiness and subsequent “unattractiveness” hair diseases cause, shorter hairstyles are often more suitable for patients experiencing diseases of the hair.
Hair diseases come in many different forms, all of which have different symptoms and varying degrees of severity. Below is an outline of the most common hair diseases and conditions.
Diseases & Hair Conditions:
Alopecia areata: Round patches of total hair loss, usually from the scalp. The cause of alopecia is unknown; the hair usually grows back.
Male pattern baldness:
The most common type of hair loss in men. Male pattern baldness usually includes either a receding hairline, hair loss at the crown, or both. The hair usually grows back.
Female pattern baldness:
In women, hair loss usually includes uniform thinning across the scalp, with a preserved hairline. The crown may be affected, but hair loss rarely proceeds to baldness as in men. See a picture of female pattern baldness. The hair usually grows back.
Dandruff (seborrheic dermatitis):
Ongoing mild inflammation of the scalp, resulting in scaly skin that may be itchy and flake off. Seborrheic dermatitis may also affect the ears and face.
Tinea capitis (ringworm):
A fungal infection of the scalp, creating round patches of hair loss. Although the patches can appear in a ring shape, no worm is involved in tinea capitis.
Trichotillomania:
A mental disorder that includes the irresistible urge to pull out one's hair. The hair pulling results in patches of noticeable hair loss; its cause is unknown.
Head lice:
Tiny insects that live on the scalp and feed on blood. Preschool and elementary school-aged children and adults who live with children are most susceptible to catching head lice, which are only spread through close contact.
Telogen effluvium:
A month or two after a personal shock (such as surgery, childbirth, severe stress), hair can abruptly fall out in large patches. Typically, new hair starts regrowing right away.
Postpartum alopecia:
hair loss after delivering a baby- is a form of telogen effluvium.
Folliculitis:
Inflammation of hair follicles, usually due to an infection. Staphylococcus aureus is a bacteria that frequently causes folliculitis. Acne is a form of folliculitis that is caused by inflammation. This inflammation can sometimes be worsened by the bacteria Propionibacterium acnes.
Piedra (trichomycosis nodularis):
Fungal infection of the hair shaft. Hard nodules made of fungus cling to hair fibers, sometimes causing hair loss.
Hirsutism:
A condition in which women develop male-pattern hair (such as facial hair). An excess of testosterone due to a medical condition is usually responsible.
Hair Shaft Abnormalities
A: With the elements the weather, lifestyle and pollution have to offer, a certain amount of breakages on our hair is expected and are completely normal. People experiencing excessively unusual amounts of hair breakage may have an abnormality within the hair shafts.
Exceptionally fragile hair and changes in density, color and length, is one of the first signs that a hair shaft abnormality may be manifesting, although without a microscopic examination or polar light microscopy of the actual hair shafts, together with a structured history and a physical examination of the patient, a diagnosis is rarely obtainable.
Trichorrhexis Nodosa:
Trichorrhexis Nodosa is one of the most common of hair diseases as it is one of the most frequent causes of hair shaft abnormalities. Trichorrhexis Nodosa usually occurs after extensive and excessive trauma is placed on the hair, which causes node like swellings to form on the shaft, which causes the hair to break easily. Whilst some experts assert that genetic factors may influence the onset of this hair disease, it is more commonly associated with environmental factors, such as excessive exposure to chemicals and aggressive brushing and blow drying.
Less commonly trichorrhexis nodosa can be caused by other underlying conditions such as hypothyroidism, Netherton’s syndrome, and Menkes syndrome. Symptoms include patchy hair, a discoloration at the tip, breakages close to the scalp, and an apparent lack of re-growth.
Like with many undesirable hair conditions, prevention is always better than cure and trichorrhexis nodosa can be readily avoided by practicing ‘kinder’ and more gentle routines to the hair. Similarly whilst there is no actual ‘cure’ for this hair disease, avoiding chemicals, harsh shampoos and excessive styling and brushing over a prolonged period of time will improve the severity of the disease and the condition of the hair.
Loose Anagen Syndrome:
Primarily loose anagen syndrome affects children with fair hair. This hair disease was first described in 1984 and is characterized by anagen hairs of abnormal morphology, which become loose and are easily dislodged from the scalp, causing the hair to become excessively thin and rarely grow beyond the nape of the neck. Loose anagen syndrome typically affects white females who are aged 2 – 5 and have blonde hair, although a small amount of cases have been reported of the disease affecting both boys and adults with darker hair.
The condition is usually detected by parents who notice their child’s hair is falling out painlessly, is dry, brittle and unmanageable, and rarely needs cutting. Unlike other hair diseases, with loose anagen syndrome the hair is not fragile or easily breakable, but rather just falls away in large clumps. A physical examination will reveal that there is no scarring or inflammation of the scalp present in patients suffering from loose anagen syndrome.
The causes of the disease are believed to be mostly hereditary, although the condition has also been
associated with other diseases, including Noonan syndrome, acquired immunodeficiency syndrome,
woolly hair, and nail-patella syndrome.
Trichotillomania:
Trichotillomania, also known as trichotillosis or trich, rather than being an actual disease of the hair, is a mental condition, which adversely affects the hair. Trichotillomania is an impulse control disorder, in which sufferers have repeated and compulsive urges to pull their hair out, with such aggression, that it often results in noticeable bald patches appearing on the head.
Because it is a mental disorder, Trichotillomania is difficult to treat and needs to be dealt with extreme caution. Low self-esteem, depression, anxiety and obsessive compulsive disorder are commonly associated with people suffering from Trichotillomania.
Signs that an individual is deliberately pulling their hair out range from the obvious bald patches visible on the head, hair of differing lengths, broken hair and blunt ends, but also some patients may be ashamed of their compulsions and be intent on ‘hiding’ the evidence by wearing wigs and hats.
Diagnosis of the disease usually comes through self-admittance, but for those who deny the disorder; tests for other diseases of the hair which result in similar symptoms need to be performed to rule them out. Because Trichotillomania is a mental condition, treatments usually consist of referrals to psychiatrists and psychologists and putting the patient on behavior modification programs rather than pharmacological interventions. Although medications related to depression and anxiety, can also be prescribed, such as Prozac and other selective serotonin reuptake inhibitors
Diagnosis of the disease usually comes through self-admittance, but for those who deny the disorder; tests for other diseases of the hair which result in similar symptoms need to be performed to rule them out. Because Trichotillomania is a mental condition, treatments usually consist of referrals to psychiatrists and psychologists and putting the patient on behavior modification programs rather than pharmacological interventions. Although medications related to depression and anxiety, can also be prescribed, such as Prozac and other selective serotonin reuptake inhibitors>
Folliculitis is a hair disease which causes inflammation of individual hair follicles, which is not restricted to the hair on the scalp but can occur anywhere on the body. When the follicles become swollen, it causes painful red bumps to appear on the skin. Folliculitis is most commonly caused by a bacterial infection, although less frequently it can be caused by non-bacterial factors including friction from tight clothing or shaving. Anybody can be affected by Folliculitis.
Tinea Capitis:
Tinea Capitis, or more commonly known as ‘scalp ringworm, is a fungal infection of the scalp. Primarily this hair disease is caused by dermatophytes which invade the hair shaft.
Symptoms are fairly easy to detect and commonly include scaly swellings of the scalp, raised red rings on the scalp, as well as dandruff and itching and bald patches occurring where the fungus ‘eats away’ at the hair.
Typically, Tinea Capitis affects pre-pubertal children, the majority of whom are boys. A microscopic examination of the scalp and hair usually confirms Tinea Capitis.
Seborrhoeic Dermatitis:
Seborrhoeic dermatitis is a disorder of the skin which affects the scalp and causes excessive itching and flakiness. Temporary hair loss readily occurs with those suffering from Seborrhoeic dermatitis and in some cases can even lead to permanent hair loss if the hair follicles are badly damaged. Environmental, hereditary, hormonal and immune-system factors have all been associated with causing Seborrhoeic dermatitis, although the exact cause remains ambiguous. Seborrhoeic dermatitis affects both adults and children.
Types of hair Shape
Q: How many types of hair Shape?
A. The amount of natural curl a hair has is determined by its cross-sectional shape.
Hair that is most similar to a circle is straight and hair that is flattened and elliptical
is curly or kinky.
The more circular the shaft is, the straighter it is. The more elliptical the shaft is, the curlier or kinkier the hair. The cross-sectional shape also determines the amount of shine the hair has. Straighter hair is shinier because sebum from the sebaceous gland can travel down the hair more easily. The kinkier the hair, the more difficulty the sebums has traveling down the hair, therefore the drier or dull the hair looks.
Almost without exception all humans have hair covering the entire surface of their body (except for the palms of our hands, the soles of our feet, and our eyelids and lips).
There are two distinct types of hair: terminal and vellus. Terminal hair is colored and visible, and can be divided into two further types:
i) Long, soft hair such as that of the head, beard, pubic and axillary (armpit) hair
ii) Short, stiff hair that makes up our eyebrows and eyelashes. Vellus hair (also called Lanugo) is the downy colorless hair that we have everywhere else.
Q: How can hair have different colors?
A: As mentioned before, there are pigment granules in the hair cortex. This pigment is called melanin and comes in two forms: eumelanin and pheomelanin. Eumelanin is the pigment we all associate with a suntan.
In the skin it acts as a protective factor against UV rays, but in hair it gives rise to black color. Ginger and brown hair colors are due to pheomelanin (more pheomelanin than eumelanin occurs in the skin of red-haired people and this is why they often suffer badly from sunburn).
Unfortunately for some, the secret of growing blonde hair is little understood. The particulars of its pigmentation are yet to be discovered…
Melanin is produced around the base of the hair by specialized cells called melanocytes for incorporation into the growing shaft. It is the progressive decrease in activity of these cells that causes hair to go 'grey' in old age.
The grey color is in fact the base color of the hair that is left behind once the melanin ceases to be incorporated. In a somewhat contradictory way, the pigment production by melanocytes actually increases with age and therefore hair can become temporarily darker before turning grey.
There is hope for those of us who would prefer not to have grey hair as one indication of progressing age. Robert Hoffman of Anticancer has recently managed to turn the hair of lab mice bright green. The gene incorporated into the cells produces a protein that is very bright green. This protein is put into the mouse hair as it grows, thus turning it green.
Using this type of vector could therefore reintroduce the genes responsible for making melanin to the cells that produce grey hairs and turn them brown again. Hoffman plans to experiment with albino mice to try and find a way of reintroducing the gene that produces melanin pigments.
Hair grows at different rates in different people; the average rate is around one-half inch per month. Hair color is created by pigment cells producing melanin in the hair follicle. With aging, pigment cells die, and hair turns gray.
Q: Why has hair at all?
A. The most significant reason for having hair is to keep warm. Though while other mammals still use their hair for this purpose, humans have lost a great deal of their covering we have not however lost the ability to make our hairs stand up on end. A tiny muscle called the arrector pili is attached to each hair follicle. This muscle contracts when in a cold environment, or when fearful. The contraction of the muscle causes the hair to be pulled downwards so that it stands up straight. This also gives rise to the 'gooseflesh' appearance of the skin. In very hairy mammals the hair now traps a significantly larger volume of warm air. The effect is like that of layer of clothing keeping warmth in. When a mammal is scared the purpose of this is to appear bigger by extending the fur outwards as far as possible.
Q: What does hair say about us?
A. A single hair from your head could tell somebody else an awful lot about you. It can reveal information about your genes, your age and even if you are a vegetarian.
DNA:
If pulled out, so that the 'bulb' is still attached, hair can provide us with information about a mammal in the form of its DNA. The DNA in the cells surrounding the bottom of the hair contains all the genetic information for that particular organism. It is a tiny amount of DNA, but with modern amplification techniques the sample is big enough to be useful. One use for this is in forensic science where hair may be left behind at the scene of a crime and the DNA contained within the hair can be matched to a suspect.