Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
The Head and the Hair in the 18–49 demographic. Liz Lemon (Tina Fey) and Jenna Maroney (Jane Krakowski) keep running into the same two men in the elevator at the 30 Rock building, and find themselves interested in them. Not knowing their names, Liz and Jenna refer to them as "The Head" (Brian McCann) and "The Hair" (Peter Hermann). After talking with Jenna, Liz decides she is going to ask "The Head" out on a date. However, on her way to find him, she runs into "The Hair", who asks her out, and discovers his name is Gray. She agrees to attend a restaurant opening