Hair anatomy

Hair - a mixed bag

A single hair contains a number of different substances, including carbon, oxygen, nitrogen, hydrogen and sulphur - and on average about 10 per cent water. The main constituent of any hair - some 90 % - is the so-called keratin, a highly structured protein also found in our upper layer of skin and in our nails.

Hair - constituents like beads on a string

As a molecule, keratin is made up of smaller units, amino acids, resembling beads on a string. The diameter of an individual hair varies from one person to the next, with the average somewhere between 0.05 and 0.09 mm. Keratin is a very durable substance, as witnessed by the virtually intact hairs found in Egyptian graves dating back centuries.

The hair shaft

The hair shaft is the visible part of any hair, i.e. outside the skin. From a technical perspective it is dead material, containing no blood vessels or nerves. This explains why having our hair cut doesn't hurt. The hair shaft consists of 3 layers:

1. The inner layer, the medulla, consisting of soft keratin and only found in thick, strong hair.
2. The middle layer, better known as the cortex and responsible for giving hair its strength, elasticity and texture. The cortex also produces melanin, the substance responsible for hair colour.
3. The outer layer is the cuticle layer. This is thin and transparent, consisting of several layers of flat, thin cells laid out overlapping one another as roof shingles. The purpose of this layer is to protect the cortex.

The hair follicle

The hair root is te part of the hair located in the follicle beneath the skin. It is the living part of any hair. The end of the hair follicle, also known as the hair bulb, is the part of the hair implanted in the skin. Each hair bulb contains a dermal papilla, consisting of a number of small blood vessels. Inside the skin, a hair follicle is covered by internal and external root sheaths, with the external sheath reaching up to the epidermis or upper skin layer.