Structure and Function of Arteries, Capillaries, and Veins. The walls of arteries and veins have three layers or tunics: 1  An outer layer (tunica adventitia) of connective tissue with collagen fibers. 2  A middle layer (tunica media) of circularly arranged smooth muscle and elastic fibers.
You might have heard that eating chocolate or greasy foods can cause acne, but these are both just myths. The truth is that food has little to do with breakouts. Acne occurs when the openings of hair follicles become blocked with oil secretions, dead skin cells and bacteria.
Alcohol can kill acne-causing bacteria on the surface of the skin, which is why some swear by alcohol-based anti-acne products to reduce their breakouts. Alcohol also quickly de-greases skin, and that instant gratification is attractive to those with super-oily complexions.