The Science of Hair

We are all quite familiar with what hair is and what it looks like.  However, by approaching the topic scientifically, we can better understand how to care for it.

Hair is made up of keratin proteins in a cylindrical form.  Hair has two separate structures, the hair follicle and the hair shaft.  The hair shaft is what we can actually see growing from our skin and scalp, while the hair follicle grows just below the surface.

The Hair Follicle grows in a protected sac-like structure that is composed of many layers.  Inside this sac are the papilla and capillaries, which nourish the hair cells, and the hair bulb.  The hair bulb is the only living part of the follicle.  Cells multiple at this level, and as they move through the root and up towards the surface, they form keratin.

A protective sheath encompasses the hair bulb and shapes the growing hair shaft.  The shape of this sheath will actually determine the hair's texture (straight, curly, wavy, etc).  Also at the hair follicle level are sebaceous glands that excrete sebum (oil).  This sebum is rich in lipids, which give the hair shine and flexibility.

The Hair Shaft is the non-living portion of the hair which is visible to the eye.  It is made up of keratin proteins and contains three different layers.

• The Medulla, the innermost layer, is a loosely formed tube of cells.  This layer isn't always present.
• The Cortex, the next layer, is built up of sulfur-rich, keratinized cells.  These cells regulate the thickness of the cortex layer and determine the physical characteristics of the hair shaft, like diameter, elasticity, color and strength.  Melanin, the component which gives hair its color, is found throughout the cortex.
• The Cuticle, the outermost layer, is made up of overlapping scales.  The cuticle acts as the protective layer of the hair shaft and is transparent.  As cells age at the cuticle level, they lose their volume and may hinder the growth of cells at the cortex level.

The hair structure consists of:

• 84% Keratin
• 12% Water
• 3% Lipids
• 1% Melanin

To maintain healthy hair, it is essential to use products that promote health at the scalp and hair level.  A healthy scalp will encourage healthy keratin production, giving you strong and naturally shiny hair.