Growth of hair is dependent on the factors like weight, age, metabolism, hormone, medications etc. all our body hair has to go through three phases. Before this let us understand how it starts. First of all a hair follicle is formed, pouch like structure under the skin and what we see is hair shaft and it is a tissue that has grown from follicle. Now the three phases of hair comes.
ANAGEN PHASE or ACTIVE GROWTH PHASE
This is a phase which lasts for several years and at a particular time, most of our body hair nearly 85% remains under this phase this time our hair has huge amount of melanin. In this phase there are many micro structures like papilla and bulge are two of them they control the growth of hair. Blood vessels are directly in contact with follicle in this stage.
CATAGEN PHASE or REGRESSIVE PHASE
During this phase hair stops growing but it has not still shed. It starts withdrawing itself from papilla and the bulge is trapped again in the skin while the hair still remains there. Now the connection with blood supply is completely stopped. Time duration for this phase is two weeks and at a particular time 3-4% hair of the body is going from catagen phase.
TELOGEN PHASE or RESTING PHASE
In this hair is ready to shed off, now it is not connected to any of the things and the process begins for new hair to grow. This phase is of 5-6 weeks and 10-13% of our total body hair is passing through this phase at a given particular time. Researches have proved that the people who remain under the stress, tension or sickness remains under this phase for more time period which result in more hair loss and reduces the re-growth.
We must have noticed that the hair on our head grows more long than the eyebrows because they remain mostly under the anagen phase and keep on growing while 10% of eyebrow hair remains under anagen phase and this process lasts for nearly three to nine weeks.
Human body has more hair follicle than the animals like gorillas, chimpanzees etc. but appear less because mostly our hair is pale and are not visible to us.