Next to each hair is a sebaceous gland which secrete sebum which lubricates the hair and provides each hair with an element of protection. If the sebaceous glands are overactive greasy or oily hair will result. If the glands are underactive dry hair may result including breakage.
Daily Hair Tip
According do stylist Kathe Swanson, Courtney Love had to have a special hairpiece pinned to her crown to give her blond mane length & fullness for the "Man In The Moon" movie.