What is the difference between an artery and a vein?

• carry blood from the tissues of the body back to the heart
• are usually positioned closer beneath the surface of the skin
• are less muscular than arteries, but contain valves to help keep blood flowing in the right direction, usually toward the heart
• would collapse if blood flow stops.

• carry blood away from the heart to the tissues of the body
• are usually positioned deeper within the body
• are more muscular than veins, which helps in transporting blood that is full of oxygen efficiently to the tissues
• would generally remain open if blood flow stopped, due to their thick muscular layer.

You may have been told that you had a heart attack or a stroke because of a blocked artery. What exactly is an artery?

Arteries, like veins, are tube-shaped vessels that carry blood in the body. The chief difference between arteries and veins is the job that they do. Arteries carry oxygenated blood away from the heart to the body, and veins carry oxygen-poor blood back from the body to the heart. 

Your body also contains other, smaller blood vessels. Here is how blood travels in vessels through the body:

Arteries transport blood containing oxygen and nutrients to smaller tubes called arterioles, which then deliver blood to even smaller vessels called capillaries. Capillaries are tiny, thin blood vessels that allow oxygen and nutrients to flow to nearby tissue. After the oxygen and nutrients have been delivered to the body's tissues by the capillaries, another network in the body carries blood back to the heart. Small tubes called venules pick up the now oxygen-poor blood and transfer it to the veins, which carry it to the heart. Once the blood has returned to the heart and been pumped through the lungs to remove carbon dioxide and receive oxygen, it is pumped back into the rest of the body and starts the process again.