Do you know that the hair on your head grows about one and a
quarter centimeters each month ? Even when your body has stopped
growing taller, you hair will still keep growing. Hair grows at ___1___
--depending on the time of the day and the time of the year. For
instance, it grows faster during the day than at night.
Similarly, it grows at a faster rate
___2___ in colder parts of
the world. Every strand of hair on your head is made up of a
root -- the soft, bulbed-shaped section under the skin, and the
shaft -- the longer strand that ___3___.
When each shaft of hair reaches a certain length, it stops
growing for it becomes too long to be properly ___4___.
It then falls out, but a new strand of hair replaces it. This
can take two to six years for the longer hair on your head, and
only three to five months for the shorter hair, such as
eyelashes and eyebrows. When a person's hair falls out and new
strands of hair do not grow as replacements, ___5___
is the result.
If you were to cut a shaft of your hair near the root and
look at a cross-section of it under a ___6___,
it would have one of two shapes: round or flat. If the
cross-section appears round, that means your hair will grow out
straight; if it appears flat, that means that your hair will
grow at different rates in different places, making ___7___.
The flatter the shaft, the curlier it will be. The shape of your
hair shaft is ___8___ the
shape of your parents' hair shaft, for this is one of the
characteristics you ___9___
from them. Some people with curly hair are unhappy with it and
have their hair straightened. Others with straight hair take
'permanent waves' to make their hair curly. Both of these
changes are ___10___,
lasting only a short time, for the shape of the shaft cannot be
changed. As that person's hair grows out, it will look the same
as before the change. |