heart4The heart is an organ made up of very strong involuntary muscles. We can’t control involuntary muscles. They move automatically.

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Our heart is an involuntary muscle. It moves all the time without us thinking about it, even when we’re asleep!

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The heart contracts and relaxes to pump blood through the blood vessels.

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The blood gives our body the oxygen and nutrients it needs.

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Video | The heart by MagicBox Animation.