Our hair structure can almost be likened to that of plants. Just like plants, our hair can be divided into two major parts:
- The Hair Root.
- The Hair Shaft.
The Hair Root is found under the scalp inside a tube-like structure called the hair follicle. Each hair follicle has a cluster of cells at the bottom responsible for making the hair grow longer called the hair bulb. There are also cells in the hair bulb called the melanocytes that produce pigment for the hair color. This pigment is called Melanin.
The Hair Shaft is the part of the hair that is visible. It is also the part of the hair we refer to as hair strands. Once the hair sprouts from the root above the scalp, it’s effectively a dead tissue and that’s why you don’t feel any sort of pain when the hair strands are cut.
The hair shaft is also made of dead cells that have turned into Keratin (protein). The hair shaft consists of three main components:
- The cuticle
- The cortex
- The medulla.
Imagine the hair shaft as an object with three different layers that you have to unravel to get to the next layer.
The cuticle is the outermost layer of the hair shaft and it protects the inside of the hair shaft from damage. It provides a significant barrier to penetration of cosmetic ingredients into the core of the hair strands.
This is the next layer, found between the cuticle and medulla and it’s the thickest of the three layers. The cortex forms the bulk of the human hair shaft. It provides flexibility, elasticity, resilience, shape, strength, curl pattern to the hair and it also contains most of the hair’s pigment.
This is the third and last layer in the hair shaft. This layer is nearly invisible and very tender. Not every strand of hair has this layer in them as it varies from strand to strand. The function of the medulla is still unknown, but it is thought to play a role in aging and depigmentation of the hair.