The Hair Growth Cycle
There are 4 phases to the lifecycle of your hair, namely Anagen, Catagen, Telogen and Exogen.
Anagen refers to the growth stage of the hair follicle. About 90% of scalp hair and 80%-85% of beard and moustache hair is in the anagen phase at any given time.
An enzyme called ornithine decarboxylase (ODC) makes the hair shaft grow. ODC only exists in anagen hairs.
The hormones testosterone and estrogens also affect hair growth. Testosterone increases hair growth except on the scalp. Estrogen inhibits hair growth making a finer less pigmented hair.
When a hair follicle completes the anagen phase it enters the catagen phase. This phase normally lasts up to 14 days, during which time the follicle shrinks to about one-sixth of its normal length.
Following the catagen phase, the hair enters the telogen phase, when the hair follicle and the dermal papilla rest. About 10%-15% of all hair is in the telogen phase at any given time, but this varies according to where the hair is on your body. When the telogen phase ends, the hair follicle begins a new anagen phase.
This is the fourth and final stage in the hair lifecycle, and it refers to hair shedding.
This is excess shedding of hair.
Alopecia refers to a condition that involves abnormal hair loss.
Facts About Hair: