Doctor Decoded: Arteries vs. Veins

Many people mistakenly believe that arteries and veins are just synonyms, and they use them interchangeably. However, these blood vessel types are different in both structure *and* function.

The quickest way to differentiate between arteries and veins is that they travel in two different directions—like an interstate with one lane traveling into downtown (the heart) and one traveling out to the suburbs (the body’s tissues).

Arteries are the heart’s delivery system, carrying oxygenated blood from the heart to the body’s tissues.

These blood vessels are made of flexible layers that can easily expand and constrict to regulate blood flow and blood pressure. For example, if you start jogging, your body demands more oxygen to meet your energy needs. Your arteries expand, allowing increased blood flow to help your muscles and organs get the nutrients they need.

Veins bring the blood back home, carrying blood from the body’s tissues back to the heart. The tissues have already used the oxygen from the blood, so blood in the veins have a reduced oxygen supply, compared to blood in the arteries.

Veins have lower blood pressure than arteries, so they have thinner and softer walls. They also have valves, which help the blood moving up to the heart instead of pooling in your hands and feet, despite gravity. At any given moment, your veins hold 70 percent of your body’s blood supply.

There’s a third type of blood vessel: capillaries. These are tiny net-like vessels that connect veins and arteries. The arteries pass blood into the capillaries, which helps transfer oxygen and nutrients to the body’s tissues, and then the capillaries pass the blood to the veins, where they are taken back to the heart and lungs to get oxygenated again.

Unfortunately, this process can encounter problems if you develop issues in the blood vessels. For example, valve problems in the veins can lead to varicose veins, and high blood pressure can lead to a weaker heart muscle over time. Here are other problems caused by high blood pressure.

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Written by:

Lauren Smith, MA

Lauren Smith, MA, has worked in health journalism since 2017. Before joining GoodRx, she was the senior health editor and writer for HealthiNation.

Reviewed by:

Alexandra Schwarz, MD

Alexandra Schwarz, MD, is a board-eligible sleep medicine physician and a board-certified family medicine physician. She is a member of both the AASM and the ABFM.

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