The normal cycle of hair growth lasts approximately up to 4 years. Each hair grows approximately 0.35 mm per day during this phase. Each hair follicle regardless the size contain a mass of cells termed the hair bulb which produces hair and hair follicles and responsible in the regeneration of new hair growth.
Under normal conditions, on an adult, 85% of the hair on the scalp is growing at any one time in the anagen phase, 1 % in it’s transitional phase (catagen) and 14% of the hair is in a resting or telogen phase.
The anagen phase last for approximately 4 years (in some people it lasts longer and may last shorter in others),the catagen phase for will last for a week and the telogen phase for approximately 3 months. Each hair follicle goes through its own independent hair growth cycle.
After 3 months, the resting hair is shed and new hair starts to grow in its place. Loss of hair is basically a result of the hair follicle loosing its capacity to initiate new growth. It is normal to shed some hair each day as part of this cycle. Every day, normal hair loss is about 20 to 80.
However, some people may experience excessive (more than normal) hair loss. Hair loss of this type can affect men, women and children. Hair thinning problems and hair fall occurs when the cycle is being aggravated by conditions such as the use of chemicals directly on the scalp, hormonal imbalances, auto immune issues or suppression and intake of medications or drugs. Other contributing factors may include: allergies, infections and metabolic and genetic disorders
Hair fall and scalp disorders are very much related to changes taking place in the normal functions of the distinct population of cells that make up the skin and its structural elements.
The scalp layer divides into 4 zones, layered one on top of the other; the epidermis, dermis, cell membranes and subcutaneous tissue. On certain parts of the body these regions and zones are highly modified, reflecting special needs, i.e. the scalp is ordinarily covered with thick hair (a product of the epidermis) and the palm is covered with a highly thickened epidermis.
On the other hand, the face contains large numbers of sebaceous glands and are susceptible to inflammation (acne). Hair, sweat glands and sebaceous glands are all specialized structures that are produced through the coordinated efforts of both epidermis and dermis. Not only do they protect the skin by regulating heat exchange; important special diseases, such as alopecia (hair loss) and acne (hair follicle inflammation) often affect them.