The Process And Cycle Of Hair Growth Explained
Hair Biology
Hair Growth Cycle
Hair grows in a tiny but powerful factory termed the hair follicle. This factory hardly ever stops working through out one's life. Each hair grows for three to five years normally. It is shampooed, conditioned, cut, blown dry, exposed to sun and wind, colored or bleached or permed during one's life time.None of these exposures have any effect on the growth process of the hair in the hair bulb. At the end of the cycle the hair is shed and after resting for some time a hair follicle starts to produce yet another new hair.
This is the hair growth cycle in a nut shell. To elaborate, between onset of production of a new hair and shedding each hair passes through three distinct stages. These stages are given special names: anagen (the growing phase), catagen (the intermediate phase) and telogen (the resting and shedding phase). The causes of baldness lie behind over or under performance of any of these phase or combinations thereof. Therefore treatments available for hair loss target the regulation of these phases.
A description of these phases is as follows:
Anagen
It is the active phase of the hair, or the 'on' phase. The typical duration of this phase in humans is roughly about 1,000 days, but it can last anything between 2 to 6 years. This phase sees the rapid division of cells in the root of the hair. The growth of the hair during this phase is about 1 cm every 28 days.A new hair shaft is formed in the follicle, which itself grows deeper into the scalp. This new hair pushes the old club hair up the follicle and eventually forces it out (the old hair is shed). The longer your Anagen phase, the longer will be the length of the hair. Hairs on the head have the longest Anagen phase as compared to the hair on the arms, legs, eyelashes, and eyebrows. That's why hairs on these places are so much shorter than scalp hair.
If the Anagen phase is affected by certain medications such as chemotherapy; or by any 'autoimmune' disease; or the harbinger of pattern baldness, the DHT hormone, hair loss and hair thinning is witnessed.
Catagen
The transitional or regressive phase, it lasts for one to three weeks. During this period, outer root sheath of a hair follicle shrinks and attaches to the root of the old hair resulting in the shrinking of the hair follicle. In fact, part of it starts to die and a club hair starts to be formed. Around 3% of all hairs are in this phase at any time. Telogen
It is the terminating stage or the 'off' phase for a hair follicle. This phase is responsible for the hairs in the bath or in your brush or comb. During this phase the hair gets separated from papilla and thus nourishment through blood stream stops. No more new hair cells are formed and only a thin strand of epidermal cells supports the inactive hair. The hair shaft is kept in its place only mechanically, and the slight tension applied while combing or drying through towel results in its shedding. At the end of this cycle only a club hair remains which is eventually pushed out and shed by a newly formed anagen hair pushing up from under the old hair.
The hair growth cycle is complete after the telogen phase. Normally the ratio of total hairs in the 'growing' anagen phase and the 'resting' phase, or telogen, is 90 to 10 respectively.
People experiencing hair thinning have a short anagen phase and a longer than usual telogen phase, resulting in more shedding than new growth. Eventually hair follicles are shut down completely and bald patches start to appear.
Now that you know what goes inside your hair when they are in grow, you can decide what would be the best treatment for it in consultation with a qualified medical professional.