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Blood Gets Around
The heart needs
helpers to make sure the blood moves all over, so it uses blood
vessels. The heart is attached to these blood vessels, which are like
pipes that carry the blood around the body. The blood vessels that carry blood
away from the heart (the fresh blood that's full of oxygen) are
called arteries, and the ones that carry
blood back to the heart (the stale blood that's carrying the
waste) are called veins. There are many veins and
arteries all throughout your body. If you lined up all the blood vessels in your
body end to end, they would wrap around the earth twice and
still have some wrapping left to do!
Listen to the Lub-dub
When you go for
a checkup, your doctor uses a stethoscope to listen
carefully to your heart. A healthy heart makes a "lub-dub"
sound with each beat. This sound comes from the valves shutting on the blood
inside the heart. The first sound (the "lub") happens when the blood hits the
mitral and tricuspid valves between the atria and ventricles. The next sound
(the "dub") happens when the blood hits the aortic and pulmonic valves that
close up as the heart relaxes to fill with blood for the next beat. Next time
you go to the doctor, ask if you can listen to the "lub-dub," too.
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