Have you ever wondered, why some people have long hair and for some people, hair just refuse to grow beyond a certain length. Just read on to find out….
Hair is mainly composed of protein called keratin and has two parts. One part is under the skin called hair follicle. Second part is the hair shaft that we see outside our skin. Dermal Papilla (DP) cells found in dermal papilla regulates hair follicle development and hair growth. Sebaceous glands produces the sebum which lubricates our hair.
The thickness and texture of our hair depends on the size of follicle at the cross-section and shape of follicle. The rounder the shape of follicle, straighter the hair will be. Also, hair will be thicker if the size of follicle is bigger. The volume of hair (number of hair on scalp) depends on the number of follicles on the scalp.
Hair Growth Cycle
Each strand of hair on human body follows a growth cycle that have different phases. Once the cycle gets completed, it sheds and a new strand of hair began to form and the growth cycle starts again. Generally hair grows around 0.5 inches per month or about 6 inches per year. A healthy human being can lose around 40-100 hair per day.
Different phases of hair growth cycle are
This is the hair growth phase. This stage can lasts from 2-6 years (sometimes longer). This phase determines how long your hair will be. The longer the phase, the longer you can grow your hair. Around 85% of hair on scalp are in the Anagen phase at any given point of time.
For example if you have a growth cycle of 2 yrs, your hair may grow approx. 12 inches and if you have cycle of 6 yrs then your might grow up to 36 inches.
After Anagen phase hair enter into next transitional phase called Catagen phase. In this stage the papilla detach itself from the hair follicle and hence it gets cut off from the nutritional blood supply. Then hair shrinks and move towards the scalp. This stage lasts for around 2 weeks. After this hair follicle enters in the Telogen phase.
This is the resting phase of hair growth and the hair follicle remains dormant at this stage. During this phase, at some point of time the follicle starts to grow again loosen the base of hair shaft and making it shed. Within two weeks the new hair shaft starts to grow and it enters in the Anagen phase and the whole growth cycle start again.
Approx. 10-15% of hair are in Telogen phase and it lasts for around 1-4 months. Sometimes due to excessive stress or other medical conditions as much as 70% hair can enter into the Telogen phase leading to excessive hair fall.
During the pregnancy, increased numbers of hair follicles remain in the anagen phase for longer periods due to hormonal changes (that is the reason hair fall stops during pregnancy) and return to the telogen phase within 3-6 months of delivery with a sudden drop in hormone levels. This results in excessive shedding of hair which most women face after the child birth.