MadSci Network: Medicine

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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