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Hair Structure, Healthy Hair Facts and Structure
Given that healthy hair is a reflection
of one's general health, it is ironic
that the visible part of a hair - the hair
shaft - is physiologically speaking,
dead, with only the tiny part underneath the scalp (the root or dermal
papilla) consisting of living hair-
forming cells known as trichocytes
and keratinocytes. The dermal papilla, nourished by a network of blood
vessels and nerves, is nestled in a
tube like hair follicle and surrounded
by what is known as the bulb. The
bulb is embedded about 4mm (0.2in)
in the subcutaneous fat of the scalp.
The outer layers of the hair bulb are
known as the outer and inner root
sheaths. It is in the dermal papilla that
most hair growth takes place. In order
for hair to grow, cells have to reproduce. This takes place around the
dermal papilla in what scientists call
the zone of proliferation.
Each hair has a protective outer
cuticle, made up of tiny overlapping
scales, often compared to miniature
roof tiles, and a thick cortex that lies
under the cuticle and consists of
the protein keratin. Keratin is also found in human skin and
nails, as well as in the feathers, claws,
hooves and wool of birds and animals.
Hair also contains the elements
carbon, oxygen, nitrogen and
sulphur and a tiny percentage of
the trace elements zinc, iron, copper
and iodine. Other components
include fats, and water, which
makes up about 12 per cent of a hair's weight.
Some type of hair - particularily thick, dark hair - also have a central medulla, which when inspected under an
optical microscope, looks a little like a
central canal. Some scientists believe
it enhances the thermal-insulation
properties of hair. Others speculate
that the medulla carries nutrients to
the cuticle and cortex, while
yet another theory is that it contributes to the shine of hair.
Hair Structure Parts
- Hair Shaft
- Medulla
- Cuticle
- Erector oili muscle
- Sebaceous gland
- Hair blub
- Papilla
- Artery
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