[chris]

Great topic.

Your daughter is quite correct in her assertion that hair has a lifespan thus accounting for its length.

Hair follicles follow a 3 phase growth cycle comprising the anagen phase, when the follicle actively makes hairs, the catagen phase, when the follicle sheds the hair and finally the thelogan phase, when the follicle rests before returning to the anagen phase again.

The lengths of these phases can vary over the body surface. Head and beard hairs have a very long anagen phase, lasing years, meaning that the hairs they produce can become very long before they drop out.

Conversely, eyebrows and eyelashes have a very short anagen phase lasting a few weeks only which means that the hairs never become very long before they are shed. You can understand the relative importance of eyelashes not exceeding a certain length otherwise they'd prevent us from seeing properly !

Hair is protein synthesised by the hair follicle and the shape and texture of hair is determined by the protein composition. Hair colour is contributed by melanocytes (melanin producing cells) within the follicles. Grey or white hairs appear when the pigment cells switch off. Presumably some cells become quiescent (enter a phase of prolonged rest) but can be genetically 'reawakened' by radiotherapy, thus accouting for some of the cases of hair mysteriously changing colour post radiotherapy.

Chris



"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[Ians Daddy]

Beautiful explanations. Thanks!

What now with the "curly / straight issue"?

Cheers!

[dalya]

As we all know I'm sure there is variation in the exact sequence of the proteins different people's cells make -most normal proteins do basically the same job but there is some flexibility in the exact code required to do it.  People with curly hair have proteins that 'di-sulphide bond' people with straight hair do not disulfide bond and those with wavy hair have an intermediate level.  Proteins are made up of different flavours of amino acids linked together linearly through peptide bonds.  However, the atoms in certain types of amino acids (sulfur to be exact) can also form bonds with amino acids that aren't sitting directly next to them.  To do this the protein must fold up and curve rather than staying completely straight.  Hence the curviness of curly and wavy hair.  Pubic hair is completely different in texture as well its curly kinky (pun abashedly intended) factor and so I think it is safe to assume that it is encoded by completely different genes than the hair on our heads.  I guess those genes encode proteins with different disulphide bonds.

Incidentally, it is inaccurate to say that any protein is completely straight because they aren't -the way in which they fold up and form a 3 dimensional structure as well as the chemical properties is what makes each protein unique and confers its functional abilities to it.  But the amount of disulphide bonding and the placement of those bonds within the hair (keratin) is what makes it curly.

[dalya]

Oh also I am sure many of you have heard about the study publshed this week stating that masturbating in your 20s reduces the risk of prostate cancer when older presumably because it clears the prostate of toxins.  no comment though in this study about how it affects baldness.  just thought this followed on well-ish from some past comments on this forum topic.

[Seek_Knowledge]

What I want to know is, is it sexual stimulation/arousal itself that triggers testosterone-DHT conversion or just ejaculation?

Is it true that PC muscle exercises can induce oxytocin and trigger testosterone-DHT conversion (something like that)?

If a man masturbates or has sex frequently but limits his ejaculation frequency to 2-3 times a week, will he have elevated DHT levels?

[yor_on]

So if one had to choose then?
Even when considering the risk of hair growing out of my ear.
I think I still would say hallo to my friend down under from time to time.
(Nope, I'm not referring to Australia).

And is that a fact?
That hairy ears equals bald heads??
That explains it...

[Profusion]

Men who lose their hair have a genetic predisposition to this, how often they have sex or all of the other activities mentioned aren't material during the loss process.  What happens is that men become sensitive to their own DHT and this causes the blood supply to be shut off to the hair root.  This is gradual, resulting in thinner weaker hair to start off with, but eventually the root is unable to produce a follicle.  There are a number of products around which are very helpful for hair loss.

[Marib-yemen]

hello folks

how do we define what is naturally head curly hair, does this type of hair grow more when one is awake or more when one is asleep.

i've also noticed that  in some people after growing head hair for a short period of time  and allowing hair to continue to grow, why does hair sometimes grow quiet fast in a sudden short period of time then grow at a ordinary rate over a longer period of time?

can this happen and why?

 [] [O8)]

[Profusion]

There is a quite a good blog about blood flow to the hair root and how this relates to hair loss on
newbielink:http://www.retaining-hair-health.com/2009/12/does-your-hair-actually-breathe.html [nonactive]

What it is saying is that your hair does not breathe, it gets its oxygen supply from the blood vessels, if these are constricted, which what happens when someone begins to lose their hair, then the blood supply is depleted, the hair follicle gets weaker and weaker and eventually the root cannot sustain a health hair follicle, which is what causes baldness.

Minoxidil as a vasodilator presumably counters the effect of the vasoconstriction and maintains the blood flow to the hair root.

[Karen W.]

hello folks

how do we define what is naturally head curly hair, does this type of hair grow more when one is awake or more when one is asleep.

i've also noticed that  in some people after growing head hair for a short period of time  and allowing hair to continue to grow, why does hair sometimes grow quiet fast in a sudden short period of time then grow at a ordinary rate over a longer period of time?

can this happen and why?

 [] [O8)]

I was once told hair thrives and grows like the seasons..winter the hair seems to grow evenly quick then spring it shoots out with the sun then summer slows down.. or something like that I may have it backwards and summer the growth spurt like most kids flouring in the warmer weather etc... sun and warmer weather increase growth...No expert but something I once heard but know not if there is any truth to that?

[Karen W.]

I do know that we shed in the warmer weather of spring and grow faster and fuller in the winter like any animals fur or hair as a defense against the cold!

[Karen W.]

So if one had to choose then?
Even when considering the risk of hair growing out of my ear.
I think I still would say hallo to my friend down under from time to time.
(Nope, I'm not referring to Australia).

And is that a fact?
That hairy ears equals bald heads??
That explains it...

Hell fire its a No Brainer loose the hair!!  LOL..LOL

Bald is beautiful.. and rather sexy too!

[Geezer]

I'm pretty sure I was warned it could actually lead to hair gain - on the palms of the hands.

[Karen W.]

.lol'''LOL..At that rate there should be more men swinging through the trees very soon!