The Hair

A hair is an appendage of the skin. It grows out of, and is part of the skin, and is made up of dead skin cells containing keratin. The palms of the hands, soles of the feet, lips and some parts of the sex organs are the only parts of the skin which are not covered in hair.

Functions of the hair

The hair has a number of different functions including insulation and protection from physical damage and the sun. The eyelashes help prevent foreign particles entering the eyes, whilst nostril hair does the same for the nose. Body hair also provides a sensory function and helps to secrete sebum on the surface of the skin.

Layers of the hair

There are three types of cells in the hair, which form different layers. The medulla is the central layer and contains soft keratin. This layer only exists in coarser hair, not thinner hair.

The pigment, along with hard keratin is found in the cortex, the thickest layer of the hair. This layer is made up of dense, elongated cells. It is these cells which contain the pigment and hard keratin. The pigment is what gives the hair its colour, and once this stops being produced, the hair becomes white. Tinting products colour the melanin in the hair, which is why grey or white hair is more difficult and time consuming to treat.

The outer layer of the hair is the cuticle. The cells contained within the layer are thin and flat, and contain hard keratin