Heyyy you guys 🙂
It only makes sense to start our discussion at the very very beginning- the very thing that we are here for. The definition of hair itself- the anatomy of it, the parts of it. That’s what we’re doing in this post, looking at the structure of hair.
Our hair strands grow out of numerous tiny pits buried in our scalp. These little pits are called follicles. All the hair on your body come from follicles. By week 22 of your stay in your mama’s belly, ALL the follicles on your body had been formed. You haven’t grown any follicles since.
Hair has two separate structures- the structure in the hair shaft (this is the hair we see) and the structure in the follicle.
At the base of the follicle is the dermal papilla, a vessel that is fed by the bloodstream with nutrients to produce new hair.
The bottom part of the follicle surrounds the papilla. It is called the hair bulb and this is the part where living hair grows. And I say living because hair is a dead cell; the bulb is the only part nourished by the capillaries in the dermal papilla. Also present in the follicle is the sebaceous gland. It produces the sebum, which is natural conditioner for the hair.
The follicle is guarded by two sheaths, the inner sheath and the outer sheath. These two protect and mold the new growing baby hair shaft. Simply put, the only living part of your hair is the part in your roots, in the bottom part of the follicle. When your hair grows, the shaft has grown out of the bulb, so it’s like pushed out and up to join the string of dead proteins. It’s like the chain of dead proteins just gets longer. A new living baby protein starts cooking in a hair bulb in a follicle.
Hair is made of a dead hard protein called keratin, the same protein that is present in your nails. Keratin is strong, resistant to wear and tear.
Each hair shaft or strand has three layers- the cortex, the medulla and the cuticle.
MEDULLA: this is the innermost layer. It is only present in large thick hairs.
CORTEX: this is the middle layer. “The main the main.” Everything about your hair- the colour, strength, curl pattern, thickness and texture is determined by the cortex. Relaxers, hair dyes and other chemical treatments work on the hair above the scalp by penetrating the cuticle to get to the cortex. There they manipulate the bonds within the cortex to get the desired result- be it straightening the curl pattern or changing the hair colour. Every single thing you apply on your hair has to get to the cortex to be of any effect. If you’re straightening your hair with a flat iron and the heat does not get to the cortex, you are wasting your time. And if too much heat gets to your cortex, that’s damage for your hair. Permanent dyes target your cortex, but non-permanent hair dyes just try to get stuck somewhere between your cuticle and your cortex.
CUTICLE: this is the outermost layer. It is thin and colourless, it protects the cortex.
The cuticle is the gate to the cortex. Some people’s cuticles are overprotective and won’t let the nutrients in. Some people’s cuticles are wide open and let too much in, but some people’s cuticles understand that there has to be a balance. It’s important to understand your own cuticle and how to get it to open or close when you need it to.
So do you now see how important it is for you to figure out the right diet and routine for your hair? It is your responsibility to manage what goes or does not go through your cuticle to your cortex. It is your responsibility to make sure anything goes through it at all. All the money you spend and effort you put in on your hair will be useless if you are not on good terms with your cuticle and if your cortex is not getting the nutrients it needs.
Are you still with me? Is any of this making sense? Next post, we’ll be revisiting the matter of Hair Typing, one of the several properties determined in the cortex and in that post (and subsequent posts) you’ll be appreciating the anatomy discussed in this post more.
Update: See the rest of the series here: Hair Basics- An Introduction to Hair 101