Hair Copy

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.


Vellus Terminal
Grows to 2cm in length



Grows inches to feet depending on area



Soft fine downy hair growth


Coarse dark terminal hair growth



Non pigmented or lightly pigmented


Heavily pigmented hair



Small root Large root with hair bulb, inner root sheath.


Shallow in depth Depth deeper than vellus but varies with area


Located all over the body except palms of hands soles of feet


Localized areas, axilla, pubic region  and scalp
Grows from lobe of sebaceous gland


Grows from dermis



Has a localized blood supply from the

sebaceous gland


Has a deep rich blood supply from the dermal papilla within the dermis




Can be stimulated to form terminal hair by topical stimulation.


Under control of hormones