The science behind our hair!
Hello there!
‘Hey,
you have beautiful hair!’ Yes, this is one of the best compliments we would
ever want to listen from either a stranger or a friend. In today’s hustle, we
all know how difficult it is to take care of and maintain healthy hair, but somehow,
we manage doing either good or worse. To have a better understanding of this
subject, let’s start from the basics.
Let’s
go!
What is that one image that pops into your mind when we say ‘hair care?’ Long, lustrous locks from a popular influencer? Or maybe a new thermal protection hairspray you have been wanting to try? Yes, while there are several images associated with this term, hair care has established an integral role in our daily lives. Hair has become a reflection of one’s identity, style, and personality. Long or short, blonde or red, curled or straight, hair care is not only a hygienic routine but also a way of expressing oneself.
Since
hair plays a key role in the way we look and feel from within, it is very
important that we give our utmost attention to maintain it. It is, therefore,
important to learn and understand the fundamentals of hair biology to help us
recognize the importance of hair shape, strength, growth, and overall
appearance. So let us all dive deep into the science of hair care.
Hair Anatomy
Our hair is composed of a keratinous filament which grows out of the epidermis. Keratin, is a group of proteins designed to provide strength, structure, and rigidity to our skin, nails, and hair all over the body. We have two different structures called hair follicle and hair shaft. Hair follicles are the living parts of the hair, while the latter is what we actually see. Hair shafts are made of dead, keratinized cells. Once damaged, the hair cannot repair itself, since it is a dead fiber. The base of hair follicles is formed by the hair bulbs, where blood vessels further nourish the cells in the hair bulb to deliver hormones which modify our hair growth and structure at different stages of life.
As
you all know, hair follicles are present all over our body except for the palms
of our hands and soles of our feet. Our body has around five million hair follicles,
with about one hundred thousand follicles on our scalp. Our scalp has the
highest density of hair follicles with three to five hundred per square
centimeter.
Our
hair shaft consists of three main components called the medulla, the cortex,
and the cuticle. The medulla is the innermost layer of this structure, which is
considered the marrow of the hair, with a soft and thin core of cells and hair
space. This layer is found in thick or coarse hair and not in fine hair. Next
up is the middle layer cortex, which provides hair its strength and flexibility,
making the majority of the hair shaft. This layer also provides color to the
hair as it contains pigmenting cells. The cuticle is the outermost layer formed
by overlapping scales.
Okay, let’s get this straight, think about shingles on a roof or fish scales and how they overlay. Just like how these scales or shingles protect the inner layers from damage, the cuticle also does the same. So, if our hair is in a good shape, it is because of the cuticles that tightly lie together, giving us that shiny and lustrous hair. And when we see hair damaged, that is when the cuticle tends to open, making the hair rough and brittle. Our hair cuticles rise up in some conditions when they are exposed to heat or alkaline materials. This condition allows the shampoo to clean our hair and also fades the hair color. The alkaline pH of the shampoo and hot water used opens the cuticles to allow the shampoo to penetrate our hair.
Cuticle
perform various functions in hair porosity by determining the passage of oil
and moisture in the hair. Some external factors such as heat, chemical
processes, and sun exposure could change the hair porosity from time to time. Hair
porosity is completely dependent on the cuticles by helping us understand the
right balance of moisture to keep our hair strong, shiny, and healthy. Also, an
easy way of testing hair porosity is by taking a bowl of water and floating the
hair strands in it. If the hair sinks, then it has a high porosity level and if
it stays in the middle of water, then it is normal, but if it floats, then it
has a low porosity level. Of course, you can try this hack at home, thank us
later!
Due
to excess use of chemicals, exposure to heat, or environmental pollution, our
cuticles tend to open wide and absorb excessive moisture through the holes
without retaining it, resulting in a high porosity level. Bleaching,
straightening, and overwashing could be the primary reasons of such a
condition. However, it is important to avoid blow-drying our hair frequently
and let the air do its job most of the time to protect our hair. Low porosity
level is when the cuticles are tightly held together by not allowing the
required moisture to penetrate. Medium porosity absorbs all the needed moisture
and retains it with ease. But you see that it is the normal path that is mostly
difficult to take. So, let us all try maintaining a medium and normal porosity
level by hydrating and moisturizing.
Straight, Curly, Wavy?
What
is your hair type? I have a curly-wavy hair type. Although we have similar
components in our hair shaft, why do we all have different hair types naturally?
It is because of the shape of our hair follicles, don’t worry I just discovered
this too! The hair follicles contain cells and connective tissues that
determine our hair shape. Straight hair has a round or circular hair follicle
while curly hair has an oval-shaped follicle. Another factor contributing to
this hair curl are follicle tunnels. If the follicles turn vertically down from
the skin’s surface, then it results in straight hair. The more the follicles
angel into the dermis, the curlier the hair shape is. We know our hair turns
gorgeous as the curls grow, but at the same time welcomes dryness. Normally, sebum
produced in sebaceous glands lubricates the hair, assisting with moisture and
shine. But it gets difficult for the sebum to travel into the curved follicles,
leading to hair dryness. Hence, straight hair tends to shine more than a curly
hair. No problem, not all of our fingers are the same.
Hair Color
Blonde,
red, black, or brown, just like our skin, even our hair gets its color from
melanin pigment produced by melanocytes. Hair color is due to two types of
melanin, including eumelanin and pheomelanin. Eumelanin causes our hair to be
brown-black, whereas pheomelanin accounts for a blonde-red color. Color
darkness is based on the presence of eumelanin, the higher the presence, the
darker our hair will be. The absence of either type produces grey or white
hair. As we all might know, melanin levels change over time, influencing a
person’s skin and hair color. Melanin levels decrease over time, resulting in
hair loss and greying.
Apart
from our natural hair, we like to try various hair colors externally to feel
new and unique, don’t we agree? Coloring has never been easier, from dyes to
bleach, we have it all. It might get easier with time, but also affects our
hair strands in various ways. Hair dyes penetrate the hair shaft by lightening
the natural pigment and depositing artificial color. Artificial hair colors’
major source is ammonia, it opens the hair cuticles to allow the hair dye to
penetrate into the cortex. As too much opening of cuticle holes leads to
variation in hair porosity level, ammonia usage is not pleasant for our hair
strands.
Some
science: Artificial hair colors are temporary, as they are large
molecules entering between the hair cuticles and coating the surface. These
colors do not last long and fade away easily, whereas semi or permanent hair
dyes are smaller molecules which penetrate the hair cuticle and enter the cortex.
Since the pigmenting cells lie in the cortex, semi or permanent hair dyes stay
a little longer than the artificial colors. However, permanent hair dyes
utilize ingredients to react with melanin naturally. These dyes might fade over
time but do not wash out. Hair lighteners or bleaching uses oxidizing
ingredients that can swell the hair and dissolve the hair’s melanin or natural
color pigments, resulting in hair lightening.
Artificial hair colors contain harsher chemicals, damaging the hair over time. Hair dye or bleach damages the cuticle layer every time and if these cuticles do not shut properly, oxidized color washes easily. Hence, leading to frequent coloring, this results in damage of hair from the roots. It is very important to take proper care and moisturization to keep our hair healthy. Organic or home-made products could come to your rescue!
Fun
fact: Coarse hair tends to take a longer time to absorb
color due to its large diameter, while fine hair absorbs hair color quickly and
easily. We can see how hair porosity levels play a role in color absorption,
washout, and dyeing.
Bonds
Our hair structure is based upon a strong protein called keratin. This protein consists of a chain of amino acids bonded together. These chemical bonds are hydrogen bonds and disulphide bonds that hold keratin together. These bonds are responsible for the shape, strength, elasticity, and shine of our hair.
Hydrogen
bonds give a temporary shape to our hair and break easily with water or heat.
These bonds reform by drying or cooling the hair. Hydrogen bonds allow us to
curl or straighten our hair. Every time wet hair dries, hydrogen atoms reform
their bonds with the neighboring strands of keratin protein and hold until the
hair is wet again. These bonds are those responsible for our bedhead, which is
what we wake up to after falling asleep with wet hair.
Disulphide bonds are also called cystine, sulphur, or S bonds that are stronger than hydrogen bonds. These bonds provide hair strength, elasticity, and resistance to breaking. Cystine is also one of the reasons of keratin’s strength, due to the presence of a sulphur-containing amino acid. The cystine forms strong cross-links with other cysteine amino acids, giving keratin the right amount of rigidity and strength. When two cysteine amino acids join, they create a cystine by a disulphide bond. Cystine is more stable than a cysteine. Though the pronunciations are the same, cysteine as amino acids are the building blocks to create cystine. Our hair structure can change due to the altering of disulphide bonds. Chemical processes such as permanent hair dyes or relaxers change the bonds and eventually hair structure. Based upon our mood, we can either straighten or curl our hair which breaks or relaxes these bonds, just like spaghetti from its dry state to cooked state.
Hair Growth
Well,
most of us have a serious concern regarding hair growth. Although hair growth
is a continuous process, we typically lose around fifty hair strands per day,
which is normal. Hair loss is a condition where more hair is shed than what is
replaced. It could be due to various reasons, such as hormonal changes, diet,
water intake, aging etc. Scientifically, hair growth occurs in three phases: the
growth phase (anagen), the transitional phase (catagen), and the resting phase
(telogen). The anagen or growth phase lasts between two and six years, where
the hair grows longer. Catagen phase is when the hair stops growing, lasting
about two weeks. The resting phase is when no new hair growth occurs. After
around two to four months, this phase ends and hair sheds as the entire process
starts over again.
Fortunately,
all our hair follicles go through these phases independently, making it not
shed all at a time. Some individuals have shorter anagen phases, contributing
to difficulty in hair growth beyond a certain length. It can also result in too
many hairs entering the telogen phase at the same time, causing too much
thinning of hair and hair loss (Yes, it might be bad, but we can get through
this by incorporating some healthy practices).
No matter what chemicals, colors, and dyes we use to style our hair, hair protection remains a key part of our daily lives. Our cuticles undergo a variety of processes to give us the hair that we have. Nevertheless, learning about the science and biology behind our strands is a great way to start our hair care.
Tune
in to Active Concepts YouTube channel to have more insights about hair biology!