The hair growth cycle

Hair grows in cycles of various stages:

•       Anagen – is the growth stage

•       Catagen – is the regressing stage

•       Telogen – is the resting stage

The hair cycle’s length varies on different parts of the body.

The whole cycle takes around 28 days.

Hair Growth Definitions
There are two main types of hair:

• Vellus
• Terminal

Vellus Hair 

Like lanugo, but not quite so fine.  Very soft, short (rarely exceeds 2cm in length), downy hair which is barely visible as it is not pigmented.  It lacks a medulla and does not have an Arrector pili muscle.
Vellus hair is found all over the body, apart from:

• Palms
  •       Soles
  •       Lips
  •       Nipples
  •       Terminal joints of the fingers
  •       Regions occupied by terminal hair

Vellus hair lie very shallowly in the skin and the growth rate is very slow as they have quite an ineffective papilla and matrix with a very poor blood supply.
The function of primary hair is to aid in the evaporation of perspiration from the body.

Terminal Hair

This is coarse, visible hair usually pigmented (except in ageing clients when greying occurs and typically found at the following body sites:
•       Scalp
•       Brows
•       Lashes
•       Nostrils
•       Ears
•       Axillae
•       Pubic region
•       Legs
•       Arms
•       Beard (males)
•       Chest (males)

Terminal hair is divided into:

Unlike vellus hair, terminal hair tends to lie deeply in the skin with a very rich blood supply to the papilla.  Often, they possess a natural curve.  Some terminal hairs increase in thickness and number with age, particularly brows and edge of ears of older men.

The function of terminal hair is protection:

• The hair of the lashes is controlled by a very sensitive reflex action which prevents foreign objects entering the eye
• The hair of the nostrils serves as protection against micro-organisms entering the body