Definition: Arteries are blood vessels that carry oxygenated blood away from the heart to various parts of the body, including the lungs and other organs. They are divided into three main types based on their shape and size: muscular arteries, which have a smooth wall and may be bifurcated or branching; elastic arteries, which have a relatively thin wall but can still carry large amounts of blood; and capillaries, which allow for the exchange of gases between blood and tissues.