There are about 5 million hairs on the body. 200,000 hairs are on the scalp.

Functions of hair

• Protects the skin from ultraviolet light
• Cushions from light blows
• Provides insulation
• Protects from sweat and foreign particles entering the eye, nose and ear.

Structure of hair

• Hair follicle – depression in the epidermis
• Papilla at the base
• Shaft
• Root
• Hair bulb

Hair is made from dead keratinised cells of differing shapes. It has three layers:

1. Cuticle – outer layer
2. Cortex – main layer of the hair.  Pigment granules are found here.
3. Medulla – inner layer (not found in all hair). Fine hairs have less medulla than course hairs.

Types of hair

• Lanugo: On body prior to birth
• Vellus: Covers body – soft and downy
• Terminal hair: Coarse hair – areas needing extra protection.
• Superflous hair refers to any unwanted hair.
• Hirsuitism refers to complete male hair growth pattern on females which is hormonally stimulated.
• Hypertrichosis is hormone stimulated growth which is considered abnormal for age, gender or race.
• Fine hair has a small or no medulla.
• Course hair has a large medulla
• Caucasian hair varies in colour and thickness, however is usually mid colour or fair.
• Asian hair is often fine and sparse and dark.
• African type hair is curly and dark.

The colour is dependent on pigmentation from melanocytes. It becomes whiter with age due to less melanin and air bubbles trapped in the shaft.