What does the heart do?
The heart is a powerful muscular organ which repeatedly contracts (tightens) and relaxes to pump blood around your body.
The heart never stops beating, even when you are sleeping.
For an average person, it beats 60 to 100 times a minute. You can feel this beat when you put your hand on your chest or take your pulse.
Your heart beats faster or slower depending on what you are doing.
- When you exercise, your heart beats faster. This is because your muscles are working harder and need more oxygen to keep going.
- When you sleep, your muscles need less oxygen, so your heart rate slows down.
Watch: Heart hearts the grind
This guy is all heart, literally, he is one! And he never stops to rest …
HEART: 'Sup everyone. It's me, the human heart. The hardest working muscle in the body. Ba boom ba boom. Oh, yeah. I'm gonna teach you how to get a hardcore work ethic like me. Ba boom! So get ready to take my advice to heart.
Because I am the human heart. Ba boom ba boom ba boom boom.
Tip one. Never stop. I'll do my job. Pumping blood around the body every single second of every single day. In fact, I'm doing it right now. And now. And now. And also now. I don't even sleep, bro. I'm working while the rest of the body is resting. What other body part can say that? The arms? Nah. The legs? Get out of here.
The kidneys?
Yeah, actually, the kidneys still keep working while you're asleep, and so does the liver and the lungs. Okay, a bunch of stuff keeps working.
But not as hard as me! Oh no sleep! Hashtag dream big, pump hard.
Tip two. Never think. For some muscles to work, the brain has to actually think about them. But not me. I just keep working all the time. Whether the brain thinks about me or not. Get out of your brain. I don't waste time with you. I just get to work, bro. Hashtag heart over mind. Breathe.
Tip three. Keep producing. I'm pumping out blood. 7000 litres every day. That's like more than four hot tubs! Four hot tubs.
Tip four!
Take time to relax.
Because I'm one big muscle. I push out blood by contracting.
And I let blood in by relaxing.
But only for a second. Because then I'm contracting again.
And then I'm relaxing.
Contracting.
Relaxing.
Contracting. Relaxing. Contracting.
And each one of those contractions is a heartbeat, bro. This muscle is grinding 24/7. Hashtag pump like a boss. Hashtag Henchheart. Hashtag King of the heart.
Um. This is embarrassing.
Well I use my muscles for pumping out blood, not picking up stuff. Hashtag I'm a heart. Not an arm. Ba boom. Heart out.
How does the heart pump blood around the body?
The heart pumps blood, which travels around the body through tubes called blood vessels.
There are three main types of blood vessels.
- Arteries carry blood away from the heart.
- Veins carry blood back to the heart.
- Capillaries are tiny blood vessels that connect arteries and veins.
The human heart is made of four chambers: two upper chambers and two lower chambers.
Blood enters the upper chambers which are called atria. These squeeze and push the blood into the lower chambers called ventricles which then squeeze and push the blood out of the heart.
The right side of the heart first pumps blood to the lungs. Here, the blood picks up oxygen that has been breathed in from the air.
The blood, now carrying oxygen, then travels back to the left side of the heart.
The heart gives the blood a second push. This time, it's sent to all the other parts of your body, including the brain, arms, legs and stomach. The blood delivers oxygen and nutrients to them all.
The blood travels back to the right side of the heart, and it all begins again.
All of this happens automatically. The brain doesn’t have to think about it, the heart just does it!
Horrible Science fact
The human heart beats one hundred thousand times a day. That’s the equivalent seven thousand litres of blood being pumped every single day. That’s more than 35 full bathtubs! It isn’t actually seven thousand litres, the average human has around 5 litres of blood, but it just keeps on going around and around and around.
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