Look! The heart is working hard to pump blood around the body.
The heart is a pump, and the blood goes round, and round, and round all the time.
And why does it do that?
Why can't it just have a rest?
Well, the blood has to be kept moving around all the time because it's the body's delivery system.
Every possible part of the body has to be supplied with oxygen and food and water, and the veins and arteries are like roads going all the way through your body with the blood cells like delivery vans.
The body is all the time shouting out:
“Over here! Delivery needed! I need oxygen! I need nutrients!”
That means that the vans are very busy indeed, all the time.
So it's a good job we've got the circulatory system to transport nutrients, water and oxygen to the entire body.
Right come on heart, back to work. Quick!
Circulatory system
Your circulatory system is made up of three parts: the heart, blood vessels and the blood itself.
Your heart keeps all the blood in your circulatory system flowing. The blood travels through a network of blood vessels to everywhere in your body. It carries useful materials like oxygen, water and nutrients and removes waste products like carbon dioxide.
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