Transcript Hair Morphology and Structure of Human Hair

Hair
Morphology and Structure of
Human Hair
- Hair consists of dead cells which
are extruded from the base of the
follicle
- Hair consist of two parts;
the shaft, the root or follicle
The hair is formed by cells of the
dermal papilla at the base of the
follicle.
 Follicles are formed during the growth
of the foetus, no new follicles are
formed post natally.
 The major function of hair is thermal
insulation.

On S.E. Microscope, the hair
shaft is seen to consist of three
regions.

The cuticle – the outer region –
encircles the cortex, and is made of 5
to 15 overlapping layers. Externally is
seen as a series of uneven edges,
which can be forced outwards by
combing or friction. There are gaps
between these layers, permitting small
molecules to enter or leave the cortex.
On S.E. Microscope, the hair
shaft is seen to consist of three
regions.
The cortex – the middle region – which has
a fibrous appearance, long strands of fibers
run along the length of the hair,
interweaving so as to form a structure of
great strength and elasticity.
 The medulla – a central canal. The cells
are nucleated near the papilla, but the cell
contents are lost they progress upwards.
Many hairs have no medulla.

Morphologically, there are
three types of hair:
Vellus : are short, fine, soft, usually non
pigmented and unmedullated
 Terminal : are large, darkly pigmented and
often medullated
90% of the hairs on the chest, trunk,
shoulders, legs and arms of men are
terminal, only 45% on women.
 Intermediate : occur on the scalp, their
morphology falls between those of terminal
and vellus and they are medullated and
contain moderate amount of pigment.

Cyclic Activity of Hair
Anagen phase: The hair grows at a
rate of about 1cm/ month, during
which the old hair is shed and new
growth begins.
Of 100,000 – 150,000 scalp hairs on
human adult, regardless of sex, 90%
are in the anagen phase
 Catagen phase: 5% resting phase
 Telogen Phase: 5%

Chemical Composition of
Human Hair
Protein (keratin) 65-95%, depending
on its moisture content
- keratin is a biopolymer composed
of 25 different amino acids, 18 in
measurable amounts
 Lipids
 Pigment and trace elements.

The extreme strength and
insolubility of hair due to:
Its large cystine content
 The filaments of the cortex are
composed of low sulphur proteins and
surrounding matrix is made up of high
sulphur proteins
 The cuticle cells do not contain any
low sulphur proteins.

The extreme strength and
insolubility of hair due to:
1- Amide links
- CO – NH –
2- Very long polypeptide chains
3- Salt links
R-NH3+ -OOCR
4- Disulpide bonds which bridges two
main chains and provides a strong
covalent link between them. R-S-S-R
5- Hydrogen bonding between the main
chains. NH ……..OC
Hair Loss

Recently, elderly became interested
in lifestyle aim to provide better diet,
nutrition and drugs that not only
target long life but also better
quality of life.
Hair Loss

Normally, around 90% of scalp follicles
are in anagen phase and 10% in
catagen and telogen phases. But many
factors can affect the cyclic activity of
hair. These factors shorten the anagen
phase, rendering terminal hair to fine
vellus hair. When anagen phase
shortens and telogen phase became
longer, considerable percentage of hair
fall out. With continuing fall of hair,
baldness becomes obvious.
Hair Loss

Aging also affect the hair cycles
rendering terminal hair into vellus,
these changes may be explained by
decreased function of hair matrix cells
that produce hair, decreased blood
flow causing shortage in nutrients,
increased sensitivity of androgenic
hormones and excess secretions of
sebum that affect the healthy
environment of hair growth.
Hair Loss
Other factors include malnutrition,
administration of certain drugs,
genetics, stress and tension may
affect the cyclic activity of hair.
 To treat hair loss, pharmaceuticals
and cosmetic firms developed new
products claimed to contain effective
ingredients to address the above
indirect causes of hair loss; include
nutrients, blood flow promoters,

Treatment of alopecia:

Finastride and dutastride : synthetic
anti-androgen taken orally to treat
pattern baldness, a form of
androgenic alopecia in men. It acts by
inhibiting 5-alpha reductase, the
enzyme that converts testosterone to
dihydrotestosterone (DHT).The U.S
Food and Drug Administration
approved finastride to treat male
pattern baldness.
Treatment of alopecia:
Minoxidil : A topical agent used to
treat hair loss . Minoxidil acts as a
vasodilator that increases blood
supply to the follicle stimulating hair
growth.
 Herbal extracts have been used to
treat alopecia. For example, Linum

usitassimum (flax) seed extract has been
used to treat male pattern baldness by
inhibiting 5-alpha reductase, thus
reducing levels of DHT.
Treatment of alopecia:

t-flavone from Hypericum perforatum
is significantly effective in treating
male-pattern and female pattern
baldness. It promotes hair growth and
increases the diameter of hair. tflavone acts by suppressing the
activation cascade of transforming
growth factor- beta 2 (TGF-B2) , a
catagen inducer secreted from the
dermal papilla .
Treatment of alopecia:


6-(Benzylamino) purine; an adenine
derivative is also used to promotes hair
growth by converting the telogen phase
in to anagen , and by stimulating DNA
synthesis, allowing lengthening of hair
shaft . [5]
Oral administration of soymetide-4, an
immunostimulating peptide derived from
soybean ,is effective in treating
alopecia. [6]
Treatment of alopecia:

The liposterolic extract of Senenoa
repens and hexane extract of
Curcuma aeruginosa are
botanically derived inhibitors of 5alpha reductase , so can be used to
treat male pattern baldness.