| HAIR
FACTS |
Effects
of damage on hair growth
Damage to the skin starts up a new growing phase in resting
follicles. Wounds cause hair growth in the skin around
them, provided there is no scarring in the follicle.
It is not true that cutting your hair makes
it grow faster or thicker. Nor does shaving your legs
make the hair grow coarser - it just feels that way. The
width of the hair shaft is determined by your genes, and
is not affected by anything you do to your skin or to
the hair shaft itself.
Effects of chemotherapy on hair patterns
Treatment of cancer with drugs may cause apparent complete
hair loss. This is because these drugs are designed to
kill cancer cells, which are cells that are growing out
of control. Other cells that are growing very actively
may be affected too: these may include cells in the bowel
lining and also in hair follicles. This leads to a 'break'
in growth and an inherent weakness. Once the drugs are
stopped the patient's hair starts to grow back, but when
it reaches the surface it tends to break. This is what
causes the apparent hair loss.
The hair that subsequently grows may may look
quite different from the old. This is because the growth
patterns of the sensitive cells of the hair bulb may still
be upset by the effects of the drug. |
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Hair patterns
Hair streams
A hair does not grow straight up out of the skin, but leaves the
follicle at a definite and predetermined angle. This angle determines
the direction along which the hair will lie, and determines the
patterns or streams that the hairs make on the head. Often the streams
spiral outwards from a central point (or points) on the crown of
the head. Usually these spirals, or 'whorls', run in a clockwise
direction.
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A
characteristic clockwise whorl of hair, with an element of unruliness
The classical 'cowlick', seen in around 7% of
children, is due to a particular hair stream on the forehead.
Unruly hair in children may be the result of scalp
hair patterning. Another possible reason is an unusual structure
of the hair shaft.
A
boy with 'cowlick' hair
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