Hair is made of protein called 'Keratin'. Hair has 2 parts, hair shaft (which is visible on the scalp) & root (which is underneath the scalp) which is responsible for the growth of hair. The hair follicle bulb manufactures cells continuously, pushing the older cells towards the surface. The cells are converted into a scleroprotein called keratin, which is then compacted to form the hair. The continuous activity of the hair follicle bulb is responsible for the growth of hair.
The hair cycle is composed of 3 stages.
- Anagen (growth phase) - 3-10 yrs (follicle actively grows hair).
- Catagen (involution phase) - 2-3 weeks (follicle is almost entirely degraded).
- Telogen (resting phase) – 3-4 months (the follicle rests prior to re-initiation of the anagen phase)
- Exogen – few weeks to months.