Structure of Hair:
The hair number which is 5 millions on human body, is about 100-150 thousands on scalp. Generally 150-200 head hair pour a day on average.
Hair includes a kind of keratin and consists of three different layers: cuticle, cortex and medulla. The cuticle is the protective part on outer layer and consists of many layers which are composed from tile-shaped cells which overlie each other. Cortex composes the large portion of hair.
The different colors and shades of hair are a result of melanin pigmentation. The melanin in the hair is substantially produced by melanocytes around of the hair. Hair turns gray with age. However real grey hair is rarely seen till the advanced ages; the hair oftenly called as grey hair is a mixture of white and pigmented hair.
Life cycle of hair consists of 3 phases: Anagen (active growth), catagen (transitional) and telogen (repose). Anagen phase lasts approximately 1000 days, katagen phase lasts a couple of weeks and telogen phase lasts about 100 days. At any time, the 5-10% of hairs is in telogen phase.
There are many reason for hair loss. But in some cases, the cause can not be found on why the hair is spilled no matter how many researchs may be done.
a) Genetic (familial) Aptitude,
b) Hair growth disorders,
c) Systemic diseases and Autoimmunity,
d) Scalp diseases,
e) Medications
effectuate the major reasons.
Normally, 50-100 hair strand in resting period of an adult may be spilled depending on hair combing or washing. These spills may last up to 2 months and repeats 3 times per year.
Local Hair Loss Causes:
Androgenic alopecia
Alopecia areata
Trichotillomania
Traction alopecia
Cicatricial alopecia
Infection
Neoplasms
Lupus erythematosus
Scleroderma
Hair Loss Reasons Observed in Each Parts Of The Scalp:
Acute blood loss
Postpartum alopecia
Protein-energy malnutrition
Weight loss
High fever
Surgery
Medications
Intoxication
Radiotherapy, secondary syphilis
