Hair grows from the hair follicles. New hair cells, produced in the follicle, eventually die to then form the new scaly hair shaft.
The dermis is the creation of strong, elastic tissue and has blood vessels nerve endings, which react to stimuli for example pain, pressure, and heat.
Hair is always in a constant growth of cycles the various phases of this cycle is anagen the hair growth phase catagen is the regressing phase and the third stage telogen is the resting phase.
The actual time these phases last will vary from person to person. Different hair colouring and the follicle shape may affect the actual timings of these phases.
anagen phase, Two – Eight years Approx
catagen phase, Two –Three weeks
telogen phase, About 3 months
Every strand of hair is composed of 3 layers:
Cuticle – Which is the outer layer
Cortex – Which is the middle layer
Medulla – Which is the inner layer
The cuticle is made up from 6 to 11 layers of overlying transparent scales made of keratin
The cortex layer provides the flexibility strength to the hair and contains melanin granules giving hair its colour.
The medulla is the innermost layer, a keratin structure with air spaces inside usually found only in thick large hair.
Hair is always going through a regular cycle of regrowth and shedding which will last a lifetime.
However, this cycle may be disrupted by genetic reasons or illness and other factors.
120,000 the average number of hairs in a full head of hair.
250 is roughly the average number of hairs that people have per square centimeter of the scalp.
Half an inch per month is roughly the rates at which hair grows.
100 microns – the average diameter of a single hair.
100 is the average number of hair we naturally lose each day.
A single strand of hair can stretch by approximately 50% before it will actually break.