Manufacturers of shampoos and conditioners often claim their products contain vitamins that are necessary to keep hair shafts healthy. Do hair shafts need vitamins? (Hint: Vitamins are required for cells to carry out certain reactions.) Why or why not? How valid are these claims?

Which of the following is not a function of body hair in humans?

a. Protection from the environment

b. Sensation

c. Protection from mechanical trauma

d. Regulation of blood flow

Fill in the blanks: The portion of the hair that projects from the surface of the skin is the____, and the portion within the dermis is the ___, which is embedded in a(n)_____ . The portion of the hair that contains cells that undergo mitosis during the growth stage of the hair is known as the                    .

Why don't you bleed when you cut your nails? Why don't you bleed when a hair is pulled?

The hair and nails are sometimes called accessory organs. Are these structures technically organs? Why or why not?