Hair Anatomy: A strand of strength and flexibility

Hair Anatomy

Hair consists of two main components; the hair root and the hair shaft.

Hair root consists of two sections: the bulb and the follicle. Hair follicle is an amazing self-renewing mini organ located below the skin which the hair strand emergers from. At the bottom of every hair follicle is a cluster of cells, nourished by blood vessels, called the hair bulb. This part of the hair is in charge of creating new hair cells, that causes the hair to emerge from the scalp and grow visibility longer. It is also responsible for producing melanin that causes the hair color. 

Your hair shaft or fibre is technically dead tissue that doesn’t contain any alive cells. If your hair gets damaged it won’t heal the way your skin does. However you may try to repair the damage with appropriate products/treatments and they can be very effective. 

Let’s take a closer look at the hair fibre. Every hair fibre consists of:

1- Inner core or cortex, and

2- Protective cuticle layer

Cortex makes up the most of hair mass (80%). Some thicker hairs may have medulla which is the innermost part of the hair shaft and is very soft and filled with air and provides thermal insulation. Cortex mostly contains keratin proteins. Keratin gives the hair its strength. There are two types of Keratin proteins: acidic type I and neutral type II which are coiled tightly together with some globular shaped proteins in between them called KAPs (Keratin Associated Proteins). The combination of the keratin and KAPs gives hair the mechanical properties of strength and flexibility. KAPs can absorb lots of water which reduces hair stiffness. You may have noticed that after styling your hair, if it is exposed to humidity the hair will become frizzy and lose its style. That is due to KAPs and their water loving properties. This can also make your hair more fragile. A wet hair stretches more than a dry hair and it also snaps much more easily and if your hair is already damaged it will snap even more easily.

Damaged Hair

Now let’s look at the cuticle, the outermost layer of the hair fibre. Cuticle cells overlap in layers creating a structure of a stack of paper cups with each cup sitting inside of another cup or like roof tiles creating a protective layer for cortex cells. If the cuticle is damaged, cortical cells will tend to split apart. This can cause split ends or breakage of the hair strand. Your hair softness and movement comes from healthy cuticles. Cuticle cells are coated with a monolayer of lipids. What this lipid layer does is that it gives your hair a water-repellent coating that makes the hair shower proof! 

Hair can become damaged through mechanical or chemical processes. Examples of mechanical damage are through washing and combing the hair. Harsh surfactants in the shampoos can stripe away the hair proteins and lipids. Heat styling and hair dryers, straightening and curling irons can also damage the hair. The heat can cause rapid evaporation of water from the hair, making it more susceptible to breakage. UV radiation from sunlight can also break the protein bonds and weaken the hair. Hair coloring, and peroxide treatment in bleaching can remove the lipid layer on the cuticles and make the hair more water loving causing hair to become prone to tangling and breakage. We are living in an era where most of these are inevitable. That makes a good hair care regimen extremely crucial in maintaining beautiful and healthy locks!

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