There are five basic types of vessels in the cardiovascular system. These vessels are responsible for either carrying oxygenated blood away from the heart to all body organs, or transporting deoxygenated blood to the heart from the organs. Without these blood vessels, the organs wouldn't receive the oxygen and nutrients needed for them to function properly. These vessels include the arteries, arterioles, capillaries, venules and veins.
Arteries
Arteries are the blood vessels responsible for carrying oxygen-rich blood away from the heart to all other areas of the body. The oxygenated blood is first pumped into the aorta, which is the main artery in the body that branches out into smaller arteries. These smaller arteries continue the transport of blood into other areas of the body, helping to supply the organs with oxygen and other nutrients needed for proper function.
Arterioles
Before the oxygenated blood makes its way to the organs and other tissue of the body, it must first go through the arterioles, which are much smaller blood vessels within the arterial system. Responsible for microcirculation, the arterioles control the amount of blood that flows into the capillaries.
Capillaries
Capillaries are the blood vessels responsible for the actual exchange of oxygen and nutrients for carbon dioxide and waste, according to the Texas Heart Institute. Capillaries are approximately the size of a hair, being so thin that they're only able to carry one blood vessel at a time to the organs and tissue of the body. Once the transfer is made, the capillaries carry the deoxygenated blood to the venules.
Venules
Venules are essentially the arterioles counterpart in those blood vessels carrying blood back to the heart. Though larger than capillaries, the venules are still rather small. They branch into the veins, helping to transport deoxygenated blood back to the heart where it can be oxygenated again.
Veins
Veins are basically the counterparts to the arteries, but instead of carrying oxygenated blood away from the heart, veins carry deoxygenated blood to the heart where it can pick up oxygen and nutrients to begin the process all over again.
