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Arteries, Capillaries, and Veins

Arteries, capillaries, and veins are the three main types of blood vessels. They are part of the cardiovascular system and work together with the heart. Without them, blood wouldn’t be able to get to all the different parts of the body.Example of Red Blood Cells.

What are Arteries?

Arteries are blood vessels that carry blood away from the heart. The blood inside of arteries has oxygen that it needs to bring to different parts of the body. Every cell in your body needs oxygen to survive. The lungs take in oxygen from the air and give it to the blood. Then the heart pumps this oxygenated blood through arteries all around the body. 
 
The heart pumps blood through the arteries with a lot of force. That is why you can feel your pulse in your arteries! Arteries have strong, thick walls to support the force of the heart pumping. 

An image of a woman taking her pulse.

When you take your pulse, you feel the blood pumping through your arteries.

There are a few major arteries in the body. The aorta is the largest artery in the body. The coronary arteries are special arteries that supply oxygen to the heart. 
 

What are Veins?

Veins are blood vessels that carry blood towards the heart. The blood inside of veins has no oxygen. Instead, it carries carbon dioxide, a gas that the body wants to get rid of. 
 
Unlike arteries, veins do not have a pulse. They are closer to the skin than arteries and their walls are less thick and muscular. The blood in veins is not pumped by the heart; instead, it flows continuously. Veins have special valves in them to make sure blood doesn’t flow the wrong way.
 
It’s easy to see veins under your skin. Try looking at your hands or wrists. Do you see your veins? Under the skin, veins appear blue, but the blood inside veins is actually dark red. It just looks blue because the skin distorts the light waves and changes the color you see. 

An image of a mand hand with veins visible under the skin.

It’s easy to see the veins in your hands. Under the skin, veins appear blue.

 

There are a few major veins in the body. The jugular veins carry blood from the head back to the heart. The venae cavae are the largest veins in the body. 
 

What are Capillaries?

Capillaries are the smallest type of blood vessel in your body. Oxygenated blood goes from the arteries to the capillaries. There, the oxygen transfers to other cells in the body. Carbon dioxide also moves into the blood cells in the capillaries. Then, the blood travels from the capillaries to the veins and returns to the heart. 

An illustration of capillaries between arteries and veins.

Capillaries allow blood to go from arteries to veins.

Capillaries are interesting because they are really really small! They are so narrow that sometimes only one blood cell can pass through at a time. Capillaries are small so that they can reach lots of different areas in the body.  
 
Watch this fun video from Crash Course: 

Other Great Resources

Kiddle Encyclopedia on Blood Vessels: https://kids.kiddle.co/Blood_vessel

Keeping Your Cardiovascular System Healthy: https://kidshealth.org/en/teens/heart.html

10 Amazing Facts About Your Blood Vessels – Everyday Health: https://www.everydayhealth.com/news/10-amazing-facts-about-your-blood-vessels/

 

Written By: Leah Tolby