Okay, I’m no scientist or physiologist, but I totally geek over anatomy and functions of the human body. Our bodies are like universes in and of themselves. How our autonomic systems function without us having to think about it, and the fact that our spirits are constantly supported and protected by our physical being is so beautiful to me.
Anyway. If you’re into that type of stuff, I think you’ll enjoy this post. We’re going to talk scalp and hair anatomy!
Disclaimer: I am not a medical professional, or doctor. The information given and products made here were obtained through research and experience. Please, as with anything you put in or on your body, consult with a medical professional if you have any concerns.
Simply put, hair is kind of important. It not only has an influential role in social and sexual interaction; it also serves as a protective barrier. Most of us know hair is a characteristic of mammals, but for the sake of simplicity, we’ll just focus humans. To keep it even more compact, we’ll focus on one type of hair called terminal hairs. The other kind are called vellus hairs, and they are the tiny, unseen type on your palms and mucous membranes like your mouth.
Terminal Hairs are the kind of hairs on your head, your eyebrows, and eyelashes. They are considered accessory organs to skin (our largest organ). They provide protection, regulation of body temperature, and facilitate evaporation of perspiration. Terminal hairs also act as sense organs.
Terminal hairs are divided into two main structures :
F O L L C L E + S H A F T
The hair follicle is the living portion of hair that is under the skin.
It is equipped with more than 2,000 sensory nerve endings- hence why it us considered a sensory organ.
The shaft is the fully-keratinized (filled with keratin protein), nonliving part above the skin surface.
Within the Shaft, there are 3 layers: cuticle, cortex and medulla.
The Medulla is the innermost layer, but is actually not present in all hair types. For example, naturally blonde and fine hair generally does not have a medulla. Crazy right!? It consists of invisible cells and air spaces.
The medulla has 3 main patterns:
Absent, fragmented, and continuous.
As mentioned, medullas are absent in blond, and fine hair. They are continuous in thick hair, and the fragmented are somewhere in-between.
The cortex forms the main bulk and pigment (color) of your hair. It consists of long keratin filaments, which are held together by disulphide and hydrogen bonds. This is where hair elasticity is determined. The health of your cortex depends largely on the integrity of the cuticle protecting it.
The cuticle is your hair’s protective layer, composed of overlapping cells — like fish scales or roof tiles, but facing downwards. A healthy cuticle is smooth and flat. This gives your hair shine and protects the inner layers from damage. It also minimizes the movement of moisture in and out of the underlying cortex, thus maintaining your hair’s hydration balance and flexibility. Chemical processes and weathering can lift the cuticle and disrupt this balance, causing your hair to become dry and brittle.
Protein + Bonds Within the Hair Shaft
Keratin is a remarkably strong protein that the hair shaft is primarily made of. It is held together by two kinds of bonds: disulphide bonds and hydrogen bonds.
Disulphide bonds are one of the strongest naturally occurring bonds in the world. When you perm, or relax your hair, these disulphide bonds are broken, and change configuration. This is what allows you to permanently change the shape of your hair.
Hydrogen bonds are weaker, but more numerous than disulphide bonds. They help give your hair its flexibility. When you wet your hair, they are easily broken and can be temporarily changed with heat until they become wet again (either from water or humidity). This is what allows you to style your hair with hair dryers and flat irons after washing.
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