Derm corner: the hair shaft

Wow I feel like an old dusty book writing this post. I bet u didn't think books had feelings....well they actually don't just incase you were second guessing yourself... :)

Anyways, I remembered my promise to post at least once a week and I was going to post last week but was away having fun in Cork for the weekend. If you havn't been you soo have to go. Its the second largest city in th republic of Ireland (and yes it has a funny name) but it's a real cool city. I think I prefer it to Dublin. I love the layout of the city...it's oozes britishness and for any one who knows me, I tend to love all things british in comparison.... Its also a very hilly city so the landscapes are just amazing.  And the people, the so called Corkonians, they are known to be very friendly people indeed. So ya, that's what I've been up to.

It's also a friends wedding this weekend and I'm planning on getting my hair straightened for hopefully the second and final time this year...and this time I'll defo be going to the brazilian salon to get it done. Can I just say that brazilians can dance...I know random to throw that in there, but my...they are real good. I tend to spend more time nowadays watching than actually dancing at the salsa nights...

Ok "re-calculating" (like the GPS woman says)...i'm having a bit of verbal diarrhea tonight largely cos I didn't get out of work till 7:30pm today and secondly cos I treated my self to some thai food +/- white wine as compensation.

Anyways so back to Derm corner...you are very welcome..pls take a seat as I continue from where I left of......... the hair shaft .........

The hair shaft is comprised of 3 layers: the outer cuticle, the inner cortex and the innermost medulla.

1. The CUTICLE- the cuticle covers the cortex...kinnda like a scales on a reptile or tiles on roofing sheets.

Roofing scales

It is basically a thin layer of cells, which may consist of as many as 5-12 sheaths. Each layer is actually anchored to the cortex below and not just simply floating in mid air. 

Interestingly,  the numbers of layers reduces from root to tip, such that at the root you can have about eleven overlapping sheaths forming one layer and at the tip about 5 or less sheaths. Likewise, with thicker stranded hairs, one tends to have more overlapping layers than thinner stranded hairs.

the real deal

The hair cuticle is the first line of defense against all forms of damage. It acts as a protective barrier for the softer inner structure (including the medulla and cortex), and is responsible for much of the mechanical strength of the hair fiber. Interestingly, the cuticle also controls the water content of the fiber, such that when it is open or raised, water entry is permitted and when closed or flat, the opposite occurs.

Y'all will probably notice that I have more information written about the cuticle than any of the other layers and this is because the condition of the cuticle determines the appearance of hair in general. Tattered, worn out cuticles reflect light poorly and the raised cuticle layers rub against each other causing friction thus preventing the hair from moving well. Much of the shine that makes healthy hair so attractive is due to the cuticle. 

In addition, Relaxers, hair dyes and some shampoos can wear away the hair's protective cuticle layers (hence why ingredient reading is so important...which we'll get to in a later post). In fact, the cuticle can get so damaged especially at the tip such that the cortex becomes fully exposed. Below are some pictures of what a damaged cuticle looks like.

Ewwwww

And you thought that was bad

Interestingly, the cuticle  is colorless; This is because it contains no melanin. The hair color we see is actually the pigmentation found in the cortex. 

Ok I think that's enough cuticle talk for one day. Moving on quickly to the next layer.

2. The CORTEX: This is the main part of the hair fibre, accounting for approx 90% of the total weight of the hair shaft. It contains spindle shaped cells made of protein and is responsible for giving hair its elasticity and curl.

3. The MEDULLA:  This is the innermost, central core of the hair shaft..kinnda like an apple core. It contains special cells that are filled with air and may or may not be present in some types of hair.It is mostly seen in terminal hairs and it's function isn't very clear.

Anyways, thats all for now folks...I'm almost dozing off.

Take care ,

XOXO

Miss Jay




References:
Pics- Google images
Text- Dermatology lecture notes by Graham brown and Tony Burns
          Clinical dermatology by Richard Weller, John Hunter, John Savin and Mark Dahl
          The science of black hair by Audrey Davis-Sivasothy
          Wikipedia