– Keratin = a fibrous protein that cells make when they are about to die.
– Cornification = the process of a cell filling up with Keratin and becoming hard.
– Follicle = the hole in the skin where they hair grows out
– Melanin = a protein that adds color to cells of the body (most familiar because they help skin tan)
Arrector pili = the muscle that makes your hairs stand up
Fingernails and hair are made out of keratinized cells. Nails are harder to protect the more tender skin below (and are a primitive tool). Hair is tightly stacked but more flexible.
Because hair grows when cells lining the follicles fill up with keratin and die, your hair grows from your scalp, rather than being added to the ends. Your hair and nails are dead cells so they don’t absorb nutrients or feel, although hair can absorb and lose moisture (thus conditioner is important).
Cells in the bulb divide every 23-72 hours.
Straight and curly hair is determined by the shape of the follicle. Symmetrical = straight, asymmetrical = curly. Square follicles is a myth.
There are 2 types of melanin – eumelanin = dark colors; pheomelanin = light. Genetics determines what ratio of each type your skin produces thus determines the color of your hair. Gray hair is produced when the cells are absent of all melanin types.