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Nov17
Hair Science and Hair Growth Cycle
Introduction:

With the beginning of the cultivation, mankind had the magnetic dip towards impressing others with their looks. The beauty of hair basically depends on individual’s health, diet, habits, job routine, climatic conditions and maintenance. Hair disorder is a common ailment of all age groups and both genders because of the infections, chemical agents & biological toxins present in the atmosphere and also due to physical factors, malnutrition and environmental pollution. The common problems occur with hair as hair fall, hair loss and their graying at an early age. They have become a general feature.

Hair Science:

Hair is far more complex than it appears on the surface. We all know that it not only plays a vital role in the appearance of both men and women, but it also helps to transmit sensory information. By week 22, a developing fetus has all of its hair follicles formed. At this stage of life there are about 5 million hair follicles on the body. There are a total of one million on the head, with one hundred thousand of those follicles residing on the scalp. This is the largest number of hair follicles a human will ever have, since we do not generate new hair follicles any time during the course of our lives. Most people will notice that the density of scalp hair is reduced as they grow from childhood to adulthood. The reason: our scalp expands as we grow.
Hair has two distinct structures – first, the follicle itself that resides in the skin and second, the shaft that is visible above the scalp.

Hair Growth Cycle:

Hair on the scalp grows about 0.3 to 0.4 mm/day or about 6 inches per year. Unlike other mammals, human hair growth and shedding is random and not seasonal or cyclical. At any given time, a random no of hairs will be in one of three stages of growth and shedding: anagen, catagen, and telogen.

Anagen:

Anagen is the active active phase of 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. Some people have difficulty in growing their hair beyond a certain length, because they have a short active phase of the growth. On the other hand, people with very long hair have a long active phase of growth. The hair on the arms, legs, eyelashes, and eyebrows have a very short active growth phase of about 30 to 45 days, explaining why they are so much shorter than scalp hair.

Catagen:

Catagen phase is transitional stage and about 3% of hair is 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 hair. This is the formation of club hair.

Telogen:

Telogen is the resting phase and usually accounts for 6% to 8% of all hair. This phase lasts for about 100 days for hair on the scalp and long for hair on the eyebrow, eyelash, arm, and leg. During this phase, the hair follicle is completely at rest and the club hair is completely formed. Pulling out a hair in this phase will reveal a solid, hard, dry, white material at the root. About 25 to 100 telogen hairs are shed normally each day.


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