8. Explain each of these familiar phenomena in terms of what you learned in this chapter: (a) pimples, (b) dandruff, (c) greasy hair and "shiny nose," (d) stretch marks from gaining weight, (e) freckles.

A. When a blocked sebaceous gland becomes infected, it produces a pimple.

B. Dandruff is the normal shedding of the stratum corneum of the scalp.

C. Greasy hair and a shiny nose both result from the secretion of sebum onto the skin.

D. Stretch marks represent small tears in the dermis, as the skin is stretched by obesity or pregnancy.

e. A freckle is a small area of pigmentation in the epidermis, caused by an accumulation of melanin.