As the heart beats, it pumps blood through a system of blood vessels, called the circulatory system. The vessels are elastic tubes that carry blood to every part of the body.
Blood is essential.
It carries oxygen and nutrients to your body's tissues
It takes carbon dioxide and waste products away from the tissues.
It is needed to sustain life and promote the health of all the body's tissues.
There are three main types of blood vessels:
Arteries
Arteries begin with the aorta, the large artery leaving the heart.
They carry oxygen-rich blood away from the heart to all of the body's tissues.
They branch several times, becoming smaller and smaller as they carry blood further from the heart.
Capillaries
Capillaries are small, thin blood vessels that connect the arteries and the veins.
Their thin walls allow oxygen, nutrients, carbon dioxide and waste products to pass to and from the tissue cells.
Veins
These are blood vessels that take oxygen-poor blood back to the heart.
Veins become larger and larger as they get closer to the heart.
The superior vena cava is the large vein that brings blood from the head and arms to the heart, and the inferior vena cava brings blood from the abdomen and legs into the heart.
This vast system of blood vessels - arteries, veins, and capillaries - is over 60,000 miles long. That's long enough to go around the world more than twice!
Blood flows continuously through your body's blood vessels. Your heart is the pump that makes it all possible.
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