The Naked Scientists
  • Login
  • Register
  • Podcasts
      • The Naked Scientists
      • eLife
      • Naked Genetics
      • Naked Astronomy
      • In short
      • Naked Neuroscience
      • Ask! The Naked Scientists
      • Question of the Week
      • Archive
      • Video
      • SUBSCRIBE to our Podcasts
  • Articles
      • Science News
      • Features
      • Interviews
      • Answers to Science Questions
  • Get Naked
      • Donate
      • Do an Experiment
      • Science Forum
      • Ask a Question
  • About
      • Meet the team
      • Our Sponsors
      • Site Map
      • Contact us

User menu

  • Login
  • Register
  • Home
  • Help
  • Search
  • Tags
  • Recent Topics
  • Login
  • Register
  1. Naked Science Forum
  2. Life Sciences
  3. Cells, Microbes & Viruses
  4. How does a hair know how long it is?
« previous next »
  • Print
Pages: [1]   Go Down

How does a hair know how long it is?

  • 1 Replies
  • 3230 Views
  • 0 Tags

0 Members and 1 Guest are viewing this topic.

Offline thedoc (OP)

  • Forum Admin
  • Moderator
  • Hero Member
  • *****
  • 510
  • Activity:
    0%
  • Thanked: 21 times
How does a hair know how long it is?
« on: 27/10/2016 23:53:01 »
rob kamstra asked the Naked Scientists:
   How does a hair, which is dead, know how long it is? If, for instance a dog [or human] is shaved, that patch of hair will grow back to exactly the length of the surrounding hair and then stop growing. Hair all over  is at differing lengths. How does the hair follicle 'get the message' to stop producing new hair?
What do you think?
« Last Edit: 27/10/2016 23:53:01 by _system »
Logged
 



Offline evan_au

  • Global Moderator
  • Naked Science Forum GOD!
  • ********
  • 11035
  • Activity:
    9%
  • Thanked: 1486 times
Re: How does a hair know how long it is?
« Reply #1 on: 28/10/2016 10:47:04 »
Hair follicles have a regular growing and resting cycle. Each new cycle pushes out the old hair and starts a new hair.

The duration of the growth cycle is different for hair on your head, eyebrows, arms, underarms or eyebrows, and this affects the maximum length that the hair will reach.

Many mammals have hair growth cycles that are synchronized to the seasons, so they may grow a long white coat in winter, and a shorter grey coat in summer, with the old hair falling out in-between.

However, human hair growth cycles are not synchronized, and so the hair remains at a constant average length, all year.

See: https://en.wikipedia.org/wiki/Human_hair_growth#Growth_cycle
Logged
 



  • Print
Pages: [1]   Go Up
« previous next »
Tags:
 
There was an error while thanking
Thanking...
  • SMF 2.0.15 | SMF © 2017, Simple Machines
    Privacy Policy
    SMFAds for Free Forums
  • Naked Science Forum ©

Page created in 0.331 seconds with 27 queries.

  • Podcasts
  • Articles
  • Get Naked
  • About
  • Contact us
  • Advertise
  • Privacy Policy
  • Subscribe to newsletter
  • We love feedback

Follow us

cambridge_logo_footer.png

©The Naked Scientists® 2000–2017 | The Naked Scientists® and Naked Science® are registered trademarks created by Dr Chris Smith. Information presented on this website is the opinion of the individual contributors and does not reflect the general views of the administrators, editors, moderators, sponsors, Cambridge University or the public at large.