Naked Science Forum

Life Sciences => Physiology & Medicine => Topic started by: lirleni on 12/09/2009 05:28:33

Title: Curly/Wavy Hair?
Post by: lirleni on 12/09/2009 05:28:33

I fully shaved my head a few months ago (and donated the hair to Locks of Love http://www.locksoflove.org/ (http://www.locksoflove.org/)). My hair is now getting long enough for the waviness to be evident and thought of this… What causes the curls or waves in hair?

I understand that the shape of the individual hairs is what causes them to be wavy/curly. what I am wondering is how all the hairs 'know' to curl/wave at the same length?

i.e. ((
     ))
     ((

rather than
  ()
  |(
  )|

Thanks!
Lirleni

Title: Curly/Wavy Hair?
Post by: Nizzle on 14/09/2009 06:41:22

Hair is curly or straight, depending upon the number of disulfide bonds between hair proteins found in the hair shaft.

The greater the number of links, the curlier the hair, and the fewer the number of links, the straighter the hair.

Hair is primarily composed of keratin, a protein, which grows from a follicle. Cells in the hair follicle generate keratin, and various other proteins, which become a part of the hair shaft. These proteins contain sulfur atoms, and when two of these sulfur atoms pair up and bond, they form a disulfide bond. If the two sulfur atoms in the same protein are at a distance, and join to form the disulfide bond, the protein will bend.

The composition of hair proteins in hair is a genetic trait, like hair color, and stays the same over the entire length of the hair. Therefore, curls/waves are about the same length

People who have long hair will see that the curls/waves are a bit stretched out closer to their head than at the hair ends. This has to do with the mechanical stress of the weight of the hair on the disulfide bonds.