How Scalp Hair Growth Works

Hair Growth Cycle Stages

Many peoples are suffering from Hair Fall because there are many causes behind it. Hence, it is necessary to understand root cause of it. Hair regrowth and Hair fall itself a complex topic than it looks on surface. Before going deeper into this topic, we need to understand the basic hair growth cycle to encounter these hairs fall causes, as a result it will help in finding out actual issue behind it.

A Hair growth takes place from inner root of the scalp called as Hair Follicle.  Hair growth takes place when all hair roots are fed by the micro blood vessels with all nutrients. Every hair is having its own life cycle and it is independent process for every individual i.e. from hair regrowth to hair fall.

So first of all, we will understand basic Hair structure then we will go through their different phases.

Hair Structure consist of two parts.

     1. Hair Follicle

  • It is a of the hair shaft which originates and resides into scalp skin i.e. which we also call as hair root.
  • Base of the follicle is papilla which contains tiny blood vessels that nourishes the hair root cells for its growth.
  • Very bottom part of the root is living part and it is surrounded by papilla, we also call as bulb.

     2. Hair Shaft

  • It is actually hair which is visible above the scalp.
  • Hair Shafts i.e. made from protein called as Keratin, but it not a living structure.

Hair shaft made and formed with three layers.

  1. Inner layer called as Medulla can be only seen in think hair.
  2. Middle layer is Cortex which makes most of the hair shafts and provides a strength, texture to hair.
  3. Outer layer called as Cuticle formed with tight structure, also it is thin and colorless.

  • Our hair colour which we see is just cortex and the medulla that holds the hair’s pigment.
  • Scalp skin having several functions according its sheath layers.

Internal sheath

  • The internal sheath follows the hair shaft and ends below the opening of a sebaceous (oil) gland.

External sheath.

  • The external or outer sheath follows all the way up to the gland. There is muscle called erector pili which attaches below the gland to a fibrous layer around the outer sheath.
  • When this muscle contracts as a result it causes hairs to stand up, also causes the sebaceous gland to secrete oil.

Furthermore it  is necessary to understand Hair growth cycle

Mainly 3 Phases of the Hair Growth Cycle

  1. Anagen
  2. Catagen
  3. Telogen


It consists of 3 stages


    • It is growing and active period of a hair follicle.
    • Time span for this stage normally lasts about 3 to 5 years.
    • Hair Span length sometimes decided by genetics in some peoples.
    • In this stage in a month hair grows takes around half an inch.
    • Hence, most of the time maximum hair growth will happen in summer season rather than any other season.
    • At any given point of time 80 to 85% of hairs on any person’s head are in the anagen phase.


    • It is transitional or intermediate period of hair growth.
    • Similarly, the deeper portion of the follicle starts getting shrinks, finally detached from the base.
    • Nourishing blood supply for this hair will be stopped, as a result of this hair growth can not happen.
    • This phase normally remains almost for 7 to 15 days.
    • While, at any given time 1 to 3% of hairs considered in this stage from overall density of hair.


    • It is resting and shedding phase of the hair cycle.
    • Hairs gets released likewise falls out from your scalp, as a result most of the time you can feel more hair fall.
    • The same root will be inactive for 1 to 4 months and new hair regrowth will takes place depend on the nutrient intake and supply it to the base root.
    • At any given point of time 10-15% of the scalp hairs are into this stage.


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