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| [
Type of Hair
| Hair
| Growth cycle
| Rate of
growth | Follicular
unit | Hair
mass ] |
|
| Growth Cycle |
| |
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| For Scalp Hair
|
| Stage
of Cycle |
Name
of Phase |
What
happens? |
Duration
|
%
of hair at a given time |
| 1st |
Anagen
(Growing)
|
New hair formation
–lengthening and thickening of hair.
|
2-6 years |
80-90% |
| 2nd |
Catagen (Intervening
or Transition) |
Round |
2-3 weeks |
1% |
| 3rd |
Telogen (shedding-resting)
|
Hair gets dislodged
and shed either on its own while washing,
brushing or by push of newly growing
hair. |
2-3 months |
10 |
|
Shedding
50 to 100 hairs a day is normal unless the
hairs you're losing aren't being replaced
by new ones. Progressive hair loss begins
naturally in both sexes about age 50, accelerating
in the 70s. About 40 percent of Caucasian
men lose hair to some extent by age 35.
When hair growth fails to keep up with hair
loss, the result is thinning hair that can
eventually lead to baldness.
In some animals all the
hairs are in the same phase at the same
time and all the hairs go through regular,
seasonal, growing and molting/shedding phases
at the same time but in humans there is
asynchronous growth i.e. not all hair shed
together, because each hair has its own
different independent growth cycle
Body hair, eyebrow hair,
eyelashes etc. all have shorter Anagen phases
and longer Telogen phases so they don't
grow as long as scalp hair.
Usually the hair you see
every day on you r brush or pillow, or in
your shower or sink is the hair that is
shed in the Telogen Phase. It will usually
be replaced by a new, growing Anagen hair.
In Androgenetic Alopecia
(common Baldness), the commonest cause of
permanent hair loss, the hormone, DHT, causes
each generation of genetically sensitive
hairs to have a shorter Anagen phase- called
miniaturized hair. The affected hairs get
progressively more fine and shorter and
lighter in colour with each growth cycle
until they finally don't grow back.
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