Welcome to Hair 102
This post is a continuation of the Introduction to Hair series, read the first installment here. We learned previously that hair is basically 'an outgrowth of dead cells' and that those cells make up the hair shaft.
The dead hair cells emerging from the follicle do so in a specific manner and arrangement. They form a strand with three layers. The first outer layer of the hair strand is the Cuticle, it comprises of a hard layer of overlapping cells. Below the Cuticle is the Cortex, this layer is the thickest and most prominent in the hair strand.
The Cortex is the powerhouse and the brain centre; it takes instructions from genes and dictates how hair forms (kinky, coily, straight). It also has the pigment with gives the strand its colour. To do anything to the hair, you have to penetrate the cuticle and get to the Cortex. It’s the boss of the whole hair structure.
Lastly, there is usually a third inner layer of the shaft called the Medulla. It is a central core of round cells. A medulla is almost always found in coarse hair, and often is absent from naturally blonde hair and very fine hair.
To dye hair, relax it or straighten it you have to manipulate the cortex, read further in Hair 103 to learn how this is done.
Well done, you're through Hair 102!