HAIR CARE

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HAIR CARE

• Original presentation by
• Assoc. Prof. Dr.Pleumchitt Rojanapanthu Pharmacy
  Department,
• Faculty of Pharmacy Mahidol University,
• Bangkok, Thailand
• Edited by Ellen Berwick

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Hair

• Getting to know hair
• Types of hair
• Hair structure
• Hair growth cycle
• Hair Color
• Physical properties of hair
• Chemical properties of hair

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Hair Care Products that affect Chemistry

• Shampoos
• Conditioners
• 2 in 1 shampoos
• Hair sprays
• Hair gels
• Perming solutions
• Hair dyes
• General remarks about product development

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Getting to Know Hair

• All land mammals including humans have hairy
  skins
• Hair characteristics (like your eyes and skin)
  are inherited directly from our parents
• hair color
• hair type

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Hair distribution

• Human are covered all over in hair except on
• the palms of hands
• the sole of the feet
• the lips
• Hair is most obvious on the head and face
• including the nose and ears in some
  people
• the armpits / the groin
• the chest and legs (in men)

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How much hair do we have

• Average 100,000-150,000 hair follicles
• Babys head 1,100 follicles/m2
• Age 25 600/m2
• Age 30-50 250-300/m2
• Each follicle grow about 20 new hairs in lifetime
• Each new hair grows several year 1 meter
• Each hair falls out eventually and is replaced
• by a new hair

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Variation in human hair

• Different people have hair that differs in color,
  length, diameter, distribution
• Influence factors Racial type and Age

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• Three types of hair

• Lanuga hair
• develops on an unborn baby
• 3 months after the babys conception
• fine and soft
• grows all over the body, at the same rate
• shed about 4 weeks before the baby is due to
  born

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• Vellus hairs
• short hair, only 1 or 2 cm long
• contains little or no pigment
• follicle doesnt have oil glands

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Terminal hairs

• long hairs that grow on the head, body, arms
• and legs
• produced by follicles with sebaceous glands
• people inherited a tendency for baldness where
  the hair become thinner and shorter until look
• like vellus hair

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• d

Vellus hairs on a womans chin. These are normal
when female hormones decline, hairs on the chin
can grow as strongly as terminal hairs
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Hair Structure
Hair follicle

• a tiny cup-shaped pit buried deep in the fat of
  the scalp
• follicle is the point from which the hair grows
• well supplied with minute blood vessels
• temperature is not affected by cold or hot water
• the rate of growth depends on the
• amount of natural light growing a little
  faster in winter when the days are short

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• Hair follicle Hair bulb
• Hair shaft
• Hair bulb
• - lines in side the hair follicle
• - is a structure of actively growing cells
• - produce a long fine cylinder of hair
• - new cells are continuously produced in the
  lower
• part of the bulb

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(a) Longitudinal section of a hair within its
follicle. (b) Enlarged longitudinal section of a
hair.
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(c) Enlarged longitudinal view of the expanded
hair bulb of the follicle which encloses
the matrix, actively dividing epithelial
cells that produce the hair.
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(d) Cross section of a hair and hair follicle.
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(e) Photomicrograph of scalp tissue showing
numerous hair follicles (24 X).
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Scanning electron micrograph showing a hair shaft
emerging from a follicle at the epidermal
surface. Notice how the scalelike cells of the
cuticle overlap one another (1500 x).
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The Hair Shaft

• can be seen above the scalp
• consist mainly of dead cells
• Keratin binding material small amount of
  water
• terminal hairs are lubricated by natural oil
  (sebum) produced by sebaceous
  glands
• high level of hormones (androgens) high
  level of sebum

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Nature of cuticle

• scales growing over the youngest part
• (closet to the scalp) are smooth and unbroken
  further along the hair have been damaged by
• cosmetic treatments and by mistreatment
  (over-energetic brushing)

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Nature of cuticle (con.)

• little by little, they may break away
• weathering
• healthy cuticle is more than just a protective
  layer
• intact cuticle cells are smooth, glossy, and
  reflect light from their surface (black hair
  reflects less light than blond hair)

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The cuticle scale on a normal hair
(electronmicrograph)
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A perfect hair seen under the electron
microscope

• Another normal hair - but this came
• from one of our nearest relatives
• an orangutan!

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Hair shape

• keratin chains link by disulphide bond and
  hydrogen bonds
• disulphide bonds can be changed by chemical
  methods perming and relaxing permanent
  
• hydrogen bonds can be easily broken apart
  whenever the hair is wetted and form again as it
  dries
• when they break the shape of hair changes
• wet hair is wound on the roller, the dried hair
  keeps the roller shape temporary

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Hair dimensions

• European around 70-90 micron
• Asian around 120 micron
• People have average hair around
• 100,000 150,000 hairs

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Hair growth cycle

• individual hair form inside a hair bulb deep in
  hair
• follicle is tiny but powerful factory
• each hair grows during many years
• shampooed, conditioned, cut, blown dry, exposal
  to the sun and wind, colored, bleached, permed
  none of these affected the hair growth
• the hair spontaneously falls out
• the follicle rests for a little while and starts
  to produce a new hair

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Stage of the hair cycle

• anagen the growing phase (1000
  days)
• catagen the intermediate phase (10 days)
• telogen the shedding phase (100
  days)

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Anagen (the growing phase)

• last between 3-7 years without interruption
• roughly 1 cm/month gt 1 meter
• faster rate in winter than summer
• melanin is made in hair bulb throughout this
  phase
• less pigment is made in older people, hair cycle
  becomes shorter
• follicles gradually give up producing long,
  strong hair
• hairs become thinner and shorter
  thinning of the hair degree of baldness

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Catagen (the intermediate phase)

• short resting phase 2-4 weeks
• no pigment is made
• follicles stop producing hair
• the base of follicle moves upwards towards the
  surface of the skin

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Telogen (the shedding phase)

• last for 3-4 months
• new hair begin to grow from the hair follicle
• as it grow s upwards the old hair will be shed
  naturally or easily be pulled out
• at anytime around one in ten of the follicles
  at individuals head is in the shedding phase
• shedding is part of normal process of the
  replacement of old hair with new hair
• new hair emerges from the same opening as the old
  one

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The hair follicle cycle
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A method of measuring the rate of hair growth
both cut hairs and newly emerging hairs can be
seen
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Electronmicrograph showing new hairs emerging
from the hair follicles of the scalp
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What controls hair growth ?

• general health and nutritional factors
• starvation or crash diet loosing hair in
  6-10
• weeks
• alcoholic people have poor hair
• some minerals may particularly important for hair
  growth

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Hair growth (con.)

• lack of Zn produces only fine, sparse hairs
• even lost their
  hairs
• Vit B known as panthenol, plays a
• part in hair
  growth, improves
• physical
  properties
• (elasticity, strength and gloss)
• of the hair
  shaft

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Hormones

• thyroid hormone speeds up growth in
• resting hair follicles
• steroids taken by mouth slow down the growth

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Hormones (con.)

• Androgen the most important factor regulating
  hair growth, thickness of hair shaft
• changes vellus - like hair
• terminal hair
• oestrogen slow down hair growth during
• growth period, make the
  period longer

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 This boy has a zinc deficiency, and his hair is
very thin and sparse after treatment his hair
is growing more strongly
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Hair Color

• Pigmentation
• Melanin - produced by melanocytes at growing
• phase (anagen)
• - spread out throughout the cortex,
  the more near outer edge
• - does not protect the harmful effect
  from
• sunlight
• - is found in 2 forms
• Eumelanin dark pigmented which
• predominates in black
  and
• brunette hair/oval
  shape
• Phaeomelain lighter pigment, found in red
• and blond hair/smaller, partly
• oval and partly rod- shape

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Melanin granules in the cortex of a hair
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Factors affecting hair structure

• the arrangement of keratin bundles
  
  the way the large bundles of keratin are
• arranged within each hair shaft
• the position of hair bulb
• African hair bulb may lie to the side of the
• follicle, so the hair shaft grows out of the
  follicle at an acute angle

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Factors affecting hair structure (con.)

• irregular growth in the hair bulb if it varies
  slightly to one side or the other, hair may grow
  wavy
• the shape of the follicle whether it is
  straight or curved
• the number of twists per unit length
• African hair has 12 times as many twist per cm.
• as Caucasian hair

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Physical properties of hair

• Strength
• Elasticity
• Static electricity
• Moisture content
• Porosity
• Texture

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Hair strength

• a single hair can support a load of about 100 gm
• keratin protein of the cortex responsible for the
  hair strength
• keratin is a protein chains contain high
  concentration of an amino acid called cystine
• matrix contains high level of cystine

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Hair strength (con.)

• each cystine unit contains 2 cysteine amino acids
  in different chain
• the chains are linked by two sulphur atoms,
• forming a very strong chemical bond
• disulphide linkage
• many disulphide bonds form down the length
• of the keratin chains

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Chemical bonds within the hair maintain its shape
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Elasticity

• one of the most important properties
• can resist forces that could change its
• shape, volume and length
• lest spring back to its original
• form without damage
• wet hair can increase the length up to 30
• and return to original length when it is dried

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Elasticity (con.)

• elasticity of hair depends on the long
• keratin fibers in the cortex
• chemical treatment can alter the cortex
• and change the hair elasticity

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Elasticity (con.)

• poor elasticity
• - stretch only to a limited extent
• - will break easily
• - cannot be permed satisfactorily
• natural sunlight and artificial UV light
• damage chemicals of hair and its elasticity

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• Static electricity
• rubbing drug hair / brushing / combing
• builds up static electric charge
• the charges tend to push each other apart
• charged hair never lie smooth against
• each other fly away hair
• stands out from the head

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• Moisture content
• Heat and humidity
• more moisture
• less static electricity
• collapse
• Heat and dryness
• less moisture
• more static electricity
• more volume

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Moisture content (con.)

• - wet hair swell cortex / lift cuticle
  scales
• - hair surface temporally loses its smoothness
• - wet hair more friction matting
  
• and tangles (over vigorous shampoo)

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Porosity Normal hair

• cuticle covering cortex is intact almost
• water proof (very little water can go in
• and out)
• shampoos do not damage the cuticle
• treating the hair (permed or tinted)

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Porosity (con.)

• temperature / applying an alkaline lotion
• separate the scale
• allowing chemicals to go inside
• after processing scales close up

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Porosity (con.)

• processing many times / too much blow
• drying/ too high temperative /
  effect
• of sun and wind
• the scales lose the tightness
• the porous
• damage cuticle is fragile
• develop split end

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Porosity (con.)

• the damage is worse as the time goes by
• the greater the damage, the more the
• cortex swells with water
• the more water loses when it dries
• repeated wetting and drying of the
• cortex, gradually weakens the hair

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Texture

• the larger the hair diameter the
• coarser it will feel
• different peoples hair naturally feel
• different soft / hard / silky / wiry
• effected by degree of weathering of hair

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Texture (con.)

• Texture is affected by what has been put
  on it
• - spray makes different feeling
• - conditioner feel soft and smooth
• - conditioner with silicone protect the
• hair cuticle
• - damage to cuticle alter the hair texture

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Chemistry of Hair

• Keratinization process in the follicle
  keratin water soluble substances pentose,
  phenols, uric acid, glycogen, glutamic acid,
  valine, leucine

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Chemistry of Hair (con.)

• Keratin is composed of amino acid

• 18 out of 25 normal amino acids
• are found in keratin

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Chemistry of Hair (con.)

• Organization of hair protein sets up by
• bonding in 3 ways

I Formation of H-bonds
between parallel peptide chains
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Chemistry of Hair (con.)
II Formation of salt linkage
between acidic and basic side chain
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Chemistry of Hair (con.)
III Formation of disulphide linkages

• amino acid contains two amino and two carlygl
• groups link together by a disulphide bond

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Structure for a- keratin