Arteries (are-te-rease): The blood vessels that carry oxygen-rich blood away from your heart for delivery to every part of your body. Arteries look like thin tubes or hoses. The walls are made of a tough outer layer, a middle layer of muscle and a smooth inner wall that helps blood flow easily. The muscle layer expands and contracts to help blood move.
In a way, moderate-intensity physical activity is that "magic pill" a lot of people are looking for, because the health benefits go beyond keeping your waistline trim: Not only can it reduce your risk of cancer, stroke, diabetes and heart attacks, but studies have shown that physical activity can significantly improve the moods of patients with major depressive disorders.