Hair

[CarolG]

How does hair know when to grow? If I shave my legs/trim eyebrows etc they grow back but for people who don't, it stays the same length. I can understand that hair will grow if its plucked but how does it know that it needs to grow more when its been cut??

[jno]

some sort of explanation here - not sure if it quite answers your question

[morg_monster]

shaving hair doesn't make any difference to the hair follicle - basically it 'doesn't know' that anything untoward has happened to the hair above the skin, so it just carries on squeezing it out as normal. So the hair continues to grow.

all hair has a 'cycle', for ladies' leg hair it is anywhere up to 1cm or longer. Once the follicle has pushed out 1cm of hair, it will stop for a while, and the root of the hair will detach from the follicle. If you didn't shave your legs then the hair would fall out in its entirety. Then it starts growing a new hair from scratch. That hair has a tapered end and feels 'soft' - like your leg hair does before you start shaving!! When you shave it it slices the top off flat and so it feels 'prickly'. Every hair has a different cycle so they don't fall out at once! (that would be quite convenient though)

[CarolG]

Many thanks to you both, that's great!