THair Anatomy
Hair
is composed of protein that grows of cells originating within the hair
follicle (why I stress the importance of protein in your daily diet). This is where the hair shaft begins.
CUTICLE
- the integrity of the hair shaft is maintained by the cuticle. The
cuticle consists of flattened cells along the hair shaft arranged like
shingles on a roof. The overlapping is extremely tight, preventing
damage to the underlying cortex. This is the part of the hair I refer to
the most, I hope you can remember these scales, they are important in
many references I will make over time. When the cuticle is intact, the
scales are smooth, reflect light, and provide a shiny, healthy look to
the hair!
Hair
is approximately 91 percent protein. 91% ! Now when I stress that PROTEIN -- PROTEIN --
PROTEIN must be burned into the back of your brain every time you go to
eat, you can now see a hint of "why". The protein is made up of long
chains of amino acids, which in turn are made up of elements. The
elements that make up human hair are carbon, oxygen, hydrogen, nitrogen,
and sulfur. These five elements are also the major elements found in
skin and nails (remember > I find so many similarities in skin and
hair - my basis for how THRIVEN was conceived) are often referred to as
the COHNS elements. Table 8-1 shows the % of each element in normal
hair.
POROSITY:
If only I could stress the importance of this characteristic, I would
be able to assess some of your hair so much easier. Porosity is the
ability of the hair to absorb moisture. The degree of porosity is
directly related to the condition of the cuticle layer therefore healthy hair
with a compact cuticle layer is naturally resistant to penetration.
Porous hair has a raised cuticle layer that easily absorbs water.
The
Texture of the hair is not an indication of its porosity. Different
degrees of porosity can be found in all hair textures. Although coarse
hair normally has a low porosity and is resistant to chemical services,
coarse hair can also have high porosity as the result of previous
chemical services.
ELASTICITY
Is the ability of the hair to stretch and return to its original length
without breaking. Hair Elasticity is an indication of the strength of
the side bonds that hold the hair's individual fibers in place. Wet hair
with normal elasticity will stretch up to 50% of its original length
and return to that length without breaking. Hair with normal elasticity
holds the curl from wet sets and permanent waves without excessive
relaxing.
As soon as these living
cells form, they begin their journey upward through the hair follicle.
They mature in a process called keratinization. As these newly formed
cells mature, they fill up with a fibrous protein called keratin, then
move upward, lose their nucleus and die. You will see many products use
that buzz word - keratin. I have performed many experiments with pure keratin, and truly did not notice any difference when it is added to the
hair strand itself. Compared to the tests with any oil by nature....the hair loves and adores anything oil based.. I even found some oil-based keratin from New Zealand that I played
around for a few months and had a little luck, the problem ended up
being if I wanted to use it in a product, it would cost me a fortune to
get it delivered from New Zealand, so I had to scratch that idea. I tell you all this so you can watch for certain names in the thousands of hair products out there.
By
the time the hair shaft emerges from the scalp, the cells of the hair
are completely keratinized and are no longer living, but the root is still alive or it wouldn't grow. The hair shaft that
emerges from the scalp is a non-living fiber composed of keratinized
protein. Hair is a cylinder of impacted keratinized cells, I have
included a simplified model of a single hair shaft (photo) and other
various close-ups for you to refer to for the discussion of hair anatomy. A cross section of the hair shaft shows you
the 3 major structures of a fully mature and keratinized hair. The
central-most layer is the medulla, the next layer is the cortex and the
outer layer is the cuticle.
MEDULLA
- this section of the hair contains melanin granules and is present
only in very thick terminal hair - generally only thick coarse hair
contains a medulla( all male beard hair contains one) its quite common
for very fine and blond hair to entirely lack a medulla. Notice the medulla is very deep and the very inside core of the hair, it is also the least
important as far as hair care.
CORTEX
- a fibrous protein core formed by elongated cells containing melanin
pigment, about 90% of weight comes from the cortex. The elasticity and
the hairs natural color begin here. Most of the changes to the hair
shaft - such as those related to permanent color (oxidative coloring),
semi permanent, chemical straightening, curling hair, permanent waving
all occur in the cortex of the hair, the major component of the hair
shaft. The cortex consists of elongated cells containing monofilament
rich in cystine, this composition gives hair its great tensile strength.
CUTICLE
- the integrity of the hair shaft is maintained by the cuticle. The
cuticle consists of flattened cells along the hair shaft arranged like
shingles on a roof. The overlapping is extremely tight, preventing
damage to the underlying cortex. This is the part of the hair I refer to
the most, I hope you can remember these scales, they are important in
many references I will make over time. When the cuticle is intact, the
scales are smooth, reflect light, and provide a shiny, healthy look to
the hair!
A healthy intact cuticle is the hair's primary defense against
damage and this is the layer that really takes the most abuse. Lets
just say > your cuticle hates your flat iron.
Hair
is approximately 91 percent protein. 91% ! Now when I stress that PROTEIN -- PROTEIN --
PROTEIN must be burned into the back of your brain every time you go to
eat, you can now see a hint of "why". The protein is made up of long
chains of amino acids, which in turn are made up of elements. The
elements that make up human hair are carbon, oxygen, hydrogen, nitrogen,
and sulfur. These five elements are also the major elements found in
skin and nails (remember > I find so many similarities in skin and
hair - my basis for how THRIVEN was conceived) are often referred to as
the COHNS elements. Table 8-1 shows the % of each element in normal
hair.
The
amino acids, the units of structure in protein, are linked together end
to end like Mardi Gras beads. the chemical bond that joins amino acids
to each other is called a peptide bond . A long chain of amino acids
linked by peptide bonds is called a polypeptide chain. Polypeptide
chains intertwine around each other in a spiral shape called a helix.
The 4 most important hair characteristics that affect its function and appearance are density, elasticity, porosity and texture. Which is an entire Department or D-E-P-T its initials.
The 4 most important hair characteristics that affect its function and appearance are density, elasticity, porosity and texture. Which is an entire Department or D-E-P-T its initials.
DENSITY
: measures the number of individual hair strands on one square inch. It indicates how many hairs there are on a persons
head. Hair density can be classified as low, medium, or high ( or thin,
medium, or thick-dense). Hair density is different from hair texture in
that different individuals with the same hair texture can have different
densities and vice-versa. Some individuals may have coarse hair texture (each hair
has a large diameter), but low hair density ( a low number of hairs on
the head). Others may have fine hair texture (each hair has a small
diameter) but high hair density ( a high number of hairs on the head).
Hope that isn't too confusing, this is an important fact for those of
you working with me on hair color consultations. The more info like this
that you can break down and explain to me the more "right-on" we will
get with your own personal hair color formulation.
The
average hair density on 1 head > about 2,200 hairs per square inch. Hair w/
high density ( thick or dense hair) has more hairs per square inch. The
average head of hair contains about 100,000 individual hair strands. the
number of hairs on the head generally varies with the color of hair.
Blondes usually has the highest density and redheads ( boo-hoo) have the
lowest.
POROSITY:
If only I could stress the importance of this characteristic, I would
be able to assess some of your hair so much easier. Porosity is the
ability of the hair to absorb moisture. The degree of porosity is
directly related to the condition of the cuticle layer therefore healthy hair
with a compact cuticle layer is naturally resistant to penetration.
Porous hair has a raised cuticle layer that easily absorbs water.
Hair
with low porosity is considered resistant (see photo) . Chemical
services performed on hair with low porosity require a more alkaline
solution than those on hair with high porosity. Alkaline solutions raise
the cuticle and permit uniform saturation and processing.
Hair
with average porosity is considered normal (see photo) . Chemical
services performed on this type of hair will usually process as
expected, according to texture, which is why if I know this about your
hair I can gauge more accurately your outcome, so I encourage all of you
to figure each of these characteristics out about your own hair, its
good information to have for life, I feel.
Hair
with high porosity is considered overly porous and is the results of
previous over processing (see photo).Over porous hair is damaged, dry,
fragile and brittle. Chemical services performed on overly porous hair
require less alkaline solutions with a lower pH. This will help over
processing.(Yes, I realize we need to go into the whole entire pH story,
which we will very very soon - it is hard to decide whether to start
with the chicken or the egg in explaining this - its ALL necessary).
The
Texture of the hair is not an indication of its porosity. Different
degrees of porosity can be found in all hair textures. Although coarse
hair normally has a low porosity and is resistant to chemical services,
coarse hair can also have high porosity as the result of previous
chemical services.
Here
is a nifty trick . . you can check porosity on dry hair by taking a
strand of several hairs from 4 different areas of the head ( the front
hairline, the temple, the crown, and the nape). Hold the strand securely
with one hand while sliding the thumb and forefinger of the other hand
from the end to the scalp. If the hair feels smooth and the cuticle is
compact, dense and hard, it is considered resistant. If you can feel a
slight roughness, it is considered porous. If the hair feels rough, dry
or breaks it is considered overly porous.
ELASTICITY
Is the ability of the hair to stretch and return to its original length
without breaking. Hair Elasticity is an indication of the strength of
the side bonds that hold the hair's individual fibers in place. Wet hair
with normal elasticity will stretch up to 50% of its original length
and return to that length without breaking. Hair with normal elasticity
holds the curl from wet sets and permanent waves without excessive
relaxing.
Hair with low elasticity is brittle and
breaks easily. Hair with low elasticity may not be able to hold the
curl from wet setting, thermal styling ( curling irons ) or perms. Hair
with low elasticity is the result of weak side bonds that usually result
from over processing. Chemical services performed on hair with low
elasticity require a milder solution with a lower pH, that solution
minimizes damage and helps prevent additional over processing.
Check
elasticity on wet hair by taking an individual strand from four
different areas of the head ( the front hairline, the temple, the crown,
and the nape). Hold a single strand of wet hair securely and try to
pull it apart ( see photo - elasticity). If the hair stretches and
returns to its original shape without breaking, it has normal
elasticity. If the hair breaks easily or fails to return to it original
length then it has low elasticity.
TEXTURE
is the thickness of diameter of the individual hair strand. Hair
texture can be be classified as coarse, medium, or fine and differs from
individual to individual (see all photos). Hair can also vary from
strand to strand on the same person's head! It is not uncommon for hair
from different areas of the head to have different textures. Hair from
the nape (back of the neck), crown, temples, and front hairline of the
same person may all have different textures - just to confuse matters
even more.
Coarse
hair texture has the largest diameter. It is stronger than fine hair,
for the same reason that a thick rope is stronger than a thin rope.
Coarse hair also has a stronger structure. It usually requires more
processing than medium or fine hair and may also be more resistant to
that processing. It is usually more difficult for hair lighteners, hair
colors, permanent waving solutions, and chemical hair relaxers to
penetrate coarse hair, so that is why this subject is relevant in the
overall scheme of hair .
Medium
hair texture is the most common and it is the standard to which other
hair is compared. Medium hair is considered normal and 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. Finer hair is hair that one should choose the least amount
of time for chemical services possible, as a safeguard. With bleach you
will be leaving it on quite a bit less than coarse hair. See why these
characteristics are so very very important ? If you figure them out
about your hair you can take them into account when coloring your hair
the first time and therefore you can avoid any disasters from happening.
Hair
Texture can be determined by feeling a single dry strand between the
fingers. Take an individual strand from 4 different areas of the head --
the front hairline, the temple, the crown, and the nape -- and hold the
strand securely with one hand while feeling it with the thumb and
forefinger of the other hand. With a little practice you will be able to
to feel the difference between coarse, medium and fine hair diameters.
These
4 major characteristics of the hair shaft, Density, Elasticity,
Porosity & Texture (dept.) -- will affect the overall permeability
of hair to chemicals and liquids of all type.Therefore how shampoo affects it as well.
Texture
and Porosity are judged together in determining the processing time.
Although porosity is more significant, texture is also important. Fine
hair, having a small diameter, will become saturated with wave lotion
more than hair with a large diameter if both are equally porous. Coarse
hair that is very porous, however will process faster than fine hair
that is not porous. The hair texture will also contribute to its
elasticity. The stronger the hair shaft, the greater its elasticity.
Whew!
that was a mouthful and page full but its something I have wanted to
get said. So I am glad it finally is. This is just the beginning of how
the hair structure pertains to shampoos,color and hair care products, which is
all forth coming so just hang on.
Killer Chemist
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