Re: Baldness in women
Area: Medicine
Posted By: David Miller, MD/PhD Student, Neuroscience
Date: Sun May 12 12:48:04 1996
I'm not really sure what you mean by "the bottom layer" of your friend's
hair, but I know why she has really thick hair. Every hair has a follicle
that is embedded in the scalp. You can think of it like a very tiny flower
pot, and each hair is like a flower that grows out of the pot. People have
different DENSITIES of hair follicles on their head. For example, some
have more hair follicles (and therefore more hairs) per square centimeter
than other people, ands therefore their hair is called "thicker".
Now, everyone has hairs that fall out all the time. It's just that we have
thousands and thousands of hairs, so losing only a few per day is not
really noticeable. Each hair follicle is programmed to grow a hair of a
certain length (say 10 centimeters). Once the hair reaches that length, it
falls out and a new hair starts growing. In this way new hairs keep
replacing the ones that fall out.
However, if there is damage to the follicle, then a new hair will not
replace the one that falls out, and baldness is the result.
The other thing I should mention is that different people's hair
follicles are programmed to grow hair of different lengths. For example,
even if I never cut my hair (which I tried doing once) it would never get
longer than my shoulder blades before falling out. Some people, however,
can grow hair that goes down to their ankles (but this is rare).
The most interesting thing about hair for me is that there is such a great
diversity of it. So many colors, styles, and thicknesses. Then again,
there's nothing wrong with baldness...just look at Michael Jordan.
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