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.
Below is a list of trigger foods for acne. If youâre experiencing breakouts, try eliminating one or two foods at a time (eliminate dairy for one week, greasy foods the next etc) to see if removing these foods helps to keep your skin clear. If you want to make sure you donât breakout, avoid all of these foods altogether as much as possible. 1. Chocolate.