We spend a lot of time worrying about the style, colour and texture of our hair, but how many of us actually know what hair is? By learning about the structure, components and growth cycles of hair, we can start to understand more about what our hair needs to be truly healthy.

 

So what is hair?

Hair is made up of the protein Keratin. This is a compound containing Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur. There are three types of hairs found on the human body:

  • Vellus which is fine and colourless
  • Intermediate that responds to hormones and grows on the pubus and axillary regions
  • Terminal which is found mainly on the scalp, and will be our focus

 

Terminal hairs are themselves composed of three concentric layers:

  • The Medulla which is the innermost layer
  • The Cortex is the thickest portion composed of flat cells containing hard keration and melanocytes
  • The Cuticle is a single layer of flattened cells, and has the appearance of scales

hair cross section

The granular pigments you can see in this diagram are the mix of blue, red and orange pigment that are naturally found in the hair. This determines the colour, and varies with nationality and race, and is also the pigment that is altered when your hair is coloured. The outer cuticle layer itself has no colour, and without any pigment inside appears white.

 

How does hair grow?

It grows from an indentation in the skin called the papilla which is nourished by a rich blood supply. As it grows through the different layers of skin, it is protected by the follicle sheath, and lubricated along the way by oil from the sebaceous gland. This oil is called sebum and protects the scalp. It is also the substance that can cause roots to look ‘greasy’.

 

There are three phases in the life cycle of a hair:

  • Anagen is the active period of growth. A scalp hair will actively grow for between 1.5 – 7 years, and the average rate of growth is 1.25cm per month. However, by a length of 25-30cm the rate of growth slows drastically to little over half it’s previous rate, and rarely grows beyond 100cm.
  • Catagen is the end of the active growth period (anagen) and when changes begin to happen in the follicle. The hair stops growing and becomes detached from the base of the follicle. Then the bulb begins to break down resulting in the follicle becoming shorter. A small section of the root remains in contact with the papilla to form a new hair. This period of change takes about 2 weeks.
  • Telogen is the resting stage, where the shortened follicle rests for 3-4 months before being ready to grow a new hair. At any one time approximately 13% of the follicles are in this resting period. However if all the follicles entered this stage at once, then the hair would moult, as with animals. Whereas in humans, the follicles are at different stages of growth so there is constant, steady shedding.

 

To keep hair as healthy as possible we therefore need to consider both the physical hair itself, and the scalp. Using strengthening and conditioning products will keep the hair shaft looking and feeling healthy. Meanwhile using gentle products will avoid irritating the scalp.

 

To discover products which are designed to be gentle to both your hair and scalp, you can read this blog about why we have developed a sulphate, sodium chloride and paraben free range.

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