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.
4. Caffeine Drinks: Caffeine drinks is the worst thing when it comes to the list of foods that cause acne as it causes the spread of acne on our skin. It is best for you to avoid any drinks which contain caffeine in your daily diet. In addition, you should avoid drinking too much coffee to maintain a smooth skin.