The arteries included in this classification are the aorta and its major branches. Elastic arteries are thick walled; having the largest diameter compared to other arteries and is the most elastic type of artery.
Their large surface area offers less resistance to blood flow, making them efficient as a transport system from the heart to the medium size arteries, hence they are sometimes called conducting arteries. The tunica media of the elastic arteries contain the most number of elastin among any other vessel type. The elastic arteries contain a substantial amount of smooth muscle but these muscles are inactive during vasoconstriction.
The elastic arteries are excellent in handling pressure, capable of expanding and recoiling in response to pressure changes as the blood is pushed out of the heart. As the heart travels through the elastic arteries, the flow is continuous regardless of the beating rhythm of the heart.
The muscular arteries are the ones that deliver blood to any specific organ in the body. Most of the named arteries being studied are under the classification of muscular arteries. Upon closer inspection, muscular arteries are just the distal portion of the elastic arteries.
The muscular arteries are also called distributing arteries. They have the thickest media among all the vessels. More smooth muscles are found in their tunica media than elastic tissue. The muscular arteries are more active in vasoconstriction because of the abundance of smooth muscles but it makes them less distensible. However, muscular arteries do contain an elastic lamina on each face of the tunica media.
The arterioles are the smallest arteries in the body, having a diameter of only 0.3 mm and some are even smaller. Even with its small size, arterioles still do have the three tunics. Their tunica media is made up chiefly of smooth muscles with a few traces of elastic fibers. The smaller arterioles, the one leading to the capillary beds, are nothing more than a single layer of smooth muscle cells that spiral around an endothelial lining.
The amount of blood that flows and reaches the capillary beds is largely determined by the diameter of the arteriole. Its varying diameter is in response to the changing hormonal, neural and local chemical influence. When the diameter of the arterioles becomes smaller, as in the case when the arterioles constrict, the tissues served will be largely bypassed. On the other hand, when the diameter of the arterioles increase, like when it dilates, the flow of blood to the local capillaries is increased exponentially.
The blood vessels can be likened to a system of expressways and roads, leading traffic to their destination. As such, they serve a very important cause, as the protector of the blood that is carrying precious cargo needed for the body to function normally.