Know the hair biology to promote and stimulate hair growth

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Hair consists 90% of α-helically coiled protein – α-keratin, and about 10% water, which modifies its mechanical properties. α-keratins form long protofibrils of about 100 µm in length and 3 µm in width. Many of these protofribrils associate to form one strand of hair, which is covered with cuticle scales. The end of each keratin chain is high in the amino acids proline and cysteine. Adjacent keratin chains are strongly linked by robust disulfide bonds.

Hair growth is a continuous process - hair generation and shedding follow back to back in a cycle. Sometimes the process is accompanied by hair loss or new hair generation. Typically, the life cycle of hair consists of three key phases:

• Anagen
  Anagen is the period of rapid keratin production. The average rate of hair growth in human scalp hair follicles is about 1/60 of an inch per day and 6 inches per year. At any time approximately 85% of all scalp hairs are in the growing phase. This phase can vary from two to six years. Hormones stimulate hair growth by influencing the activities in the follicle and keratin production.
  
  
  

• Catagen
  Anagen is followed by Catagen and lasts only one to two weeks. In this phase the follicle winds down its rapid metabolism, shrinks, wrinkles and contracts. And at certain time it stops producing keratin. In this phase the hair follicle shrinks to about 1/6 of the normal length, the lower part is destroyed and the dermal papilla breaks away to rest below.
  
  
  
• Telogen
  Telogen is the resting phase, and occurs when the follicle stops shrinking. Approximately 10-15% of all hair are in this phase at any time. This period lasts for 3-4 months during which the hair rests in the follicle until it is physically dislodged by brushing, washing, combing or massaging. It is replaced by a new hair which grows in the same follicle as the old one. The dermal papilla and the base of the follicle join together again and a new hair begins to form. The hair growth starts all over again.

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