Why do we have veins?

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If you look at some parts of your body, like the back of your hand, you may be able to see some faint, squiggly lines under your skin. They may even seem to branch out like trees! These are blood vessels, and veins are one of the three main types of blood vessel.

Every cell in our bodies needs blood because blood carries nutrients and oxygen, which our cells use as fuel. Our bodies contain trillions of cells! Luckily our blood has a way to travel around to all these cells by using a huge network of tubes called blood vessels. Blood that is full of oxygen and nutrients is pumped from the heart through tubes called arteries. From arteries, the blood enters smaller tubes called capillaries. Capillaries are so small that blood cells have to travel through them single file. Inside capillaries, the nutrients and oxygen are absorbed by our cells.

After that, it’s time for the blood to be sent back to the heart so it can be pumped again and pick up more nutrients and oxygen. The blood vessels for the return trip are called veins. A lot of time, though, people use the word vein to refer to any blood vessel in our bodies. 

Setting the Table

The next time you are getting ready to sit down for a family meal, ask a grown-up if you can help set the table. You’ll actually be acting a lot like a blood cell when you do!

The table you’re setting needs plates and food so that you can eat dinner. You’ll probably start in the kitchen. You can pick up a plate, like blood picks up oxygen from the lungs. You travel to the table. The path you take will be like an artery! Once you deliver the plate, you’ll need to come back to pick up more. The return trip will be like a vein. Your next trip to the table, maybe with a napkin, will be another trip through an artery.

A blood cell has a very busy life! Luckily for you, eventually the table will be all set up and you can sit down and enjoy a relaxing dinner, while your blood cells keep working inside your body.