Functions of Hair

Hair is a very important part of the body, and it performs many different functions. The function it performs depends on the location of the hair. For example, head hair protects the scalp from the suns rays so it won't get burnt easily. Eyebrows and eyelashes keep dust particles or anything of that matter out of the eye. The hair in your nostrils or ear canal keeps out dust, debris, or even insects from entering the body. Human body hairs also act as a sensory receptor that allows us to feel and also act as a warming sense as well.

http://www.livestrong.com/article/76153-function-human-hair/