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Author Topic: How come hair seems to know how long to or fast to grow?  (Read 2118 times)

Ellingson, Kenneth L

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Ellingson, Kenneth L  asked the Naked Scientists:

How come hair seems to know how long to or fast to grow? For example; why does the hair on your head keep growing while the hair on your arm stops when its no more than an inch long? Isn't hair dead cells?

Knute Ellingson, Chicago

What do you think?


 

Offline MonikaS

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How come hair seems to know how long to or fast to grow?
« Reply #1 on: 20/12/2008 09:43:11 »
It's not the hair itself. The hair follicle makes the hair, and in different regions of the body those follicles are genetically programmed differently. It's genetically determined for how long a hair grows until it reaches the phase, where it simply sits in its follicle and doesn't grow. After that it falls out and is replaced by a new hair.
 

Offline iko

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How come hair seems to know how long to or fast to grow?
« Reply #2 on: 20/12/2008 11:20:52 »
It's not the hair itself. The hair follicle makes the hair, and in different regions of the body those follicles are genetically programmed differently. It's genetically determined for how long a hair grows until it reaches the phase, where it simply sits in its follicle and doesn't grow. After that it falls out and is replaced by a new hair.

...and never forget that on top  (epi-) of any programmed mechanism, surrounding cells plus hormones, nutrients, cytokines, metals, poisons, and many other factors play a role.
Epigenetically.

ikod



http://www.thenakedscientists.com/forum/index.php?topic=13541.0

« Last Edit: 21/12/2008 16:30:10 by iko »
 

Offline MonikaS

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How come hair seems to know how long to or fast to grow?
« Reply #3 on: 20/12/2008 11:54:52 »
Yeah, male baldness is a prime hormonal example of this.
 

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How come hair seems to know how long to or fast to grow?
« Reply #3 on: 20/12/2008 11:54:52 »

 

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