PROPERTIES OF THE
HAIR
AND
SCALP
What is the technical term for the
study of hair, and it’s diseases
and care?
TRICHOLOGY
A mature strand of hair is
divided into two parts:
1. HAIR ROOT
2. HAIR SHAFT
STRUCTURES
OF THE HAIR
ROOT
The Follicle – tube-like pocket
which protects the root
Hair Root- the part located below
the surface of the scalp
Hair Shaft – the portion of the
hair that projects above the
skin
The Hair Bulb – lowest part of
the hair strand. Fits over the
papilla
The Arrector Pili Muscle – tiny,
involuntary muscle. Causes
goose bumps
Sebaceous Glands – oil glands of the skin, connected to hair follicles. Produces oil
called sebum which lubricates the hair and skin
Epidermis – top layer of the skin.
Dermis – the layer of the skin under the epidermis
STRUCTURE OF THE HAIR
SHAFT
There are three main layers of the hair shaft:
Cuticle
Cortex
Medulla
CUTICLE
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•
•
•
Outermost layer of the hair.
Consists of overlapping layer of cells that
look like shingles on a roof
Protects the cortex
Responsible for creating the shine and
the smooth, silky feel of healthy hair
CORTEX
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•
•
•
Middle layer of the hair
Contains melanin pigment
90% of total weight comes from the cortex
Elasticity and natural colour located in the
cortex
MEDULLA
• Innermost layer
• Quite common for very fine
and naturally blonde hair to
entirely lack one
• All male beard hair contains
a medulla
• Medulla is not involved in
salon services
CHEMICAL COMPOSITION
OF HAIR
• Composed of a protein called KERATIN
• 90% protein – made up of long chains of
amino acids which in turn are made of
elements
• COHNS elements are the 5 elements that
make up human hair and are found in the
skin and nails
• CARBON, OXYGEN, NITROGEN,
SULFUR and HYDROGEN
SIDE BONDS OF THE CORTEX
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•
•
•
•
3 different side bonds
HYDROGEN
SALT
DISULFIDE BONDS
Side bonds hold the keratin fibres and are
responsible for the strength and elasticity of
human hair
• Important for roller sets, thermal styling, perming
and chemical relaxing
HYDROGEN BOND
• Is a weak physical side bond
• Easily broken by water or heat
• Eg. Wet set
(roller set)
SALT BOND
• Also weak, temporary side bond
• Easily broken by strong alkaline
or acidic solutions
• Eg. Some mild permanent waves
DISULFIDE BOND
• Chemical side bond that is very different from
the other two.
• Are much stronger, far fewer of them
• Disulfide bonds joins to sulfur atoms to create a
cystine
• Not broken by heat or water
• Thio perms break disulfide bonds which are then
reformed by thio neutralizers
• Hydroxide chemical hair
relaxers break disulfide bonds
and they can never be
reformed
HAIR PIGMENT
• All natural hair colour is the result of the
pigment located within the cortex called
MELANIN.
• MELANIN are tiny grains of pigment that
give natural colour to hair.
• There are two different types of melanin:
Eumelanin and Pheomelanin
EUMELANIN
• Provides brown and black colour to hair
PHEOMELANIN
• Provides colours ranging from red and
ginger to yellow/blonde tones.
HAIR ANALYSIS
Different types of hair react differently to the
same service
Essential that a thorough analysis be
performed prior to all salon services
The four most important factors to consider
in hair analysis are:
texture, porosity, elasticity and density.
Also consider growth patterns and dryness
versus oiliness
HAIR TEXTURE
• Is the thickness or diameter of the
individual hair strand.
• Can be classified as coarse, medium, or
fine
• It is not uncommon for hair from different
areas of the head to have different
textures.
Coarse Hair is stronger than fine hair and usually
requires more processing time and is often more
resistant to processing.
Medium Hair texture is the most common and is
the standard to which other hair is compared.
Medium hair does not pose any special
problems or concerns
Fine Hair has the smallest diameter and is more
fragile, easier to process, and more susceptible
to damage from chemical services than coarse
or medium hair.
HAIR DENSITY
• Measures the number of
individual hair strands on 1
square inch of scalp.
• Can be classified as thin,
medium or thick/dense.
• Different from hair texture in
that individuals with the same
hair texture can have different
densities
HAIR POROSITY
• Is the ability of the hair to
absorb moisture
• Healthy hair with a compact
cuticle layer is naturally
resistant
• Porous hair has a raised
cuticle layer that easily
absorbs moisture
HAIR ELASTICITY
• Is ability of the hair to stretch and return to its
original length without breaking
• Is an indication of the strength of the side bonds
that hold the hair’s individual fibres in place.
• Wet hair with normal elasticity will stretch up to
50% of its original length and return to that same
length without breaking
• Dry hair stretches about 20% of its length
• Hair with low elasticity is brittle and breaks easily
GROWTH PATTERNS
It is important when shaping and styling hair
to consider the hair’s growth patterns.
Most hair follicles grow at an angle other
than 90 degrees, and most hair grows in a
direction other than straight out from the
head.
These growth patterns result in hair streams,
whorls, and cowlicks.
Hair Stream is hair flowing in the same direction,
resulting from follicles sloping in the same
direction. Two streams flowing in opposite
directions form a natural part in the hair.
Whorl is hair that forms in a circular pattern,
as on the crown. A whorl normally forms in
the crown with all the hair from that point
growing down.
Cowlick is a tuft of hair
that stands straight
up. Cowlicks are
usually more
noticeable at the
front hairline, but
they may be located
anywhere.
DRY HAIR AND SCALP
• Can be caused by inactive sebaceous gland,
and aggravated by excessive shampooing or dry
air, such as during winter or in a desert climate.
• Lack of sebum leads to hair that appears dull,
dry and lifeless
• Should be treated with products that
contain moisturizers and emollients
• Frequent shampooing should be
avoided, along with the use of
strong soaps or products with a
high alcohol content
OILY HAIR AND SCALP
• Caused by improper shampooing or overactive
sebaceous glands, and is characterized by a
greasy build up on the scalp and an oily coating
on the hair
• Can be treated by properly washing with a
normalizing shampoo
• A well-balanced diet, exercise,
regular shampooing, and good
personal hygiene are essential
to controlling oily hair and scalp
HAIR GROWTH
• 2 main types of hair found on the body:
VELLUS and TERMINAL HAIR
VELLUS: also known as lanugo
• Short, fine and downy
• Not pigmented and almost never has a medulla
• Found nearly everywhere except the palms of
the hands & soles of the feet
• Vellus hair helps in the efficient evaporation of
perspiration
TERMINAL HAIR:
• Is the long hair found on the scalp, legs,
arms, and bodies of males and females.
• Coarser than vellus hair and with the
exception of grey hair, it is pigmented
• Usually has a medulla and is easily
distinguished from vellus hair by its dark
colour and coarse texture
• All hair follicles are capable of producing
either vellus or terminal hair, depending on
genetics, age and hormones
GROWTH CYCLES OF HAIR
Hair growth occurs in cycles. Each
complete cycle has three phases that are
repeated over and over again throughout
life.
Anagen
Catagen
Telogen
Factors that Influence Hair Growth
• Diet
• Blood Circulation
• Emotion
Disturbances
• Endocrine Glands
• Medication
• Heredity
• Environment
• Products
• Appliances