How did our Hair grow?
Hair Growth Cycle:
The Hair on the scalp grows about .3 to .4 mm/day or about 6 inches per year. There are three main of the hair growth cycle:
- Anagen (Growth phase)
- Catagen (Transitional phase)
- Telogen (Resting phase)
Anagen is the active phase of the Hair. The cells in the root of the Hair are dividing rapidly. A new hair is formed and pushes the club hair ( a hair that has stopped growing or is no longer in the anagen phase) up the follicle and eventually out. During this phase, the Hair grows about 1 cm every 28 days. Scalp hair stays in this active phase of growth for two to six years.
The catagen phase is a transitional stage, and about 3% of all hairs are in this phase at any time. This phase lasts for about two to three weeks. Growth stops, and the outer root sheath shrinks and attaches to the root of the hat. This is the formation of what is known as a club hair.
Telogen is the resting phase and usually accounts for 6% to 8% of all hairs. This phase lasts for about 100 days for hairs on the scalp and longer for hairs on the eyebrow, eyelash, arm, and leg. During this phase, the hair follicle
is entirely at rest, and the club hair is completely formed. Pulling out Hair in this phase will reveal a solid, hard, dry, white material at the root. About 25 to 100 telogen hairs are shed, usually each day.
70% of men and 40% of women may be affected by Androgenetic alopecia at some points of their lifetime. Although it can affect both men and women, men experience a much higher degree of hair loss. It is caused by a combination of genetic and hormonal (Hidydrotestosterone- DHT) factors. In androgenetic alopecia, hairs become smaller in diameter shorter in length and lighter in color until eventually the hair follicles shrink completely and stop producing hair.
Androgenetic alopecia looks different in males and females. Hairs in the affected areas are initially smaller in diameter and shorter in length and lighter in color compared to hairs in unaffected areas before they become absent.
In men, the usual pattern of hair loss is a receding hairline, and loss of hair from the top and the front of the head. In women, hair loss or thinning typically occurs at the crown of the scalp, with complete or nearly complete preservation of the frontal hairline.
Alopecia areata is thought to be an auto-immune disease, initially appearing as a rounded bare patch about an inch across. Alopecia areata affects both men and women equally and is often experienced first in childhood.
As Alopecia areata is an auto-immune disease, this means that the body’s immune system acts as if the hair follicles are foreign and attacks them. White blood cells called T-lymphocyte to attack the hair follicle, which causes the hair to stop growing and enter into the telogen (resting) phase, after that about three months, when the resting stage is over the Hair will then fall out. Only when T-Lymphocyte stop attacking the hair follicle will new Hair grow.