How Your Heart Pumps Blood
Your heart is a fist-sized muscle in the middle of your chest, tilted slightly to the left, that pumps blood around your body without ever taking a break. It is divided into four hollow rooms called chambers — two on top (the atria) and two on the bottom (the ventricles) — and each heartbeat is a squeeze that pushes blood out, followed by a relax that lets it fill up again. That squeeze-and-relax makes the familiar 'lub-dub' sound.
Blood travels in a continuous loop, a bit like cars going round a racetrack. It collects oxygen from the lungs, gets pumped out to the rest of the body, drops off oxygen and food at every cell, then returns to the heart to start again. Along the way it also carries away waste the cells don't need.
Understanding the heart helps children make sense of why they have a pulse, why exercise makes the heart beat faster, and how the circulatory system keeps the whole body alive — a core idea in primary science.
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Meet your heart❤️ How Your Heart Pumps Blood Right now, deep inside your chest, a busy little muscle is squeezing over and over to keep you alive. Let's find out how it works! Quick fact: Your heart never takes a break — not even when you sleep. It beats about 100,000 times every day! 💪 Tap Next → to start exploring.
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A pump the size of your fistWhere is your heart? Your heart sits in the middle of your chest, leaning a little to the left. It is about the same size as your own clenched fist. Make a fist and hold it to your chest — that's roughly how big your heart is! Size of a fist 👊 Made of muscle 💪 Tilts left ⬅️
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The four roomsFour rooms inside Your heart has 4 rooms called chambers. Tap each glowing room to learn what it does! Top Right Top Left Lower Right Lower Left 👆 Tap a room above to reveal its job… Rooms explored: 0 / 4 Blue rooms hold blood that needs oxygen. Red rooms hold fresh blood full of oxygen, ready to zoom around your body. 🩸
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Lub-dub: the squeezeHow the pump works: lub-DUB A heartbeat is a squeeze. The muscle tightens to push blood out, then relaxes to fill up again. Press the button to watch one beat, step by step. Ready to beat ❤️ ▶ Beat once Doctors hear this squeeze as a “lub-dub” sound through a stethoscope.
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The big loopBlood travels in a loop Blood goes round and round in a loop, like cars on a racetrack. 🏎️ Put the journey in the right order — tap the steps from first to last. 1→ 2→ 3→ 4 🫁 Picks up oxygen in the lungs ❤️ Heart squeezes it out 🦵 Delivers oxygen to the body ↩️ Tired blood returns to the heart ↺ Start over
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Feel your heartbeatTap along with a heartbeat Every squeeze sends a little push through your body — that's your pulse. Tap the heart in time, like a steady drum. Try to reach 10 taps! 🥁 ❤️ 0 taps When you run or jump, your body needs more oxygen, so your heart beats faster to keep up. That's why your chest goes thump-thump after sports! 🏃
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Why it mattersWhy does blood matter? Blood is like a delivery truck. 🚚 It carries oxygen and food to every tiny part of your body, and takes away the rubbish your cells don't need. 🫁Lungs add fresh oxygen to your blood. ❤️Your heart pumps the blood everywhere. 🩸Blood vessels are the roads blood travels on. 💪Every muscle gets the energy it needs to move. Take care of your heart: play and exercise, drink water, sleep well, and eat fruit and veggies. A happy heart keeps you strong! 🌟
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You did it!🎉 Great work, heart explorer! Here's everything you discovered today: 👊Your heart is a muscle about the size of your fist. 🏠It has 4 rooms (chambers) that fill and empty. ❤️It squeezes (lub-dub) to push blood out. 🔁Blood travels in a loop: lungs → heart → body → back. 🩸Blood delivers oxygen so your whole body can work. Now put your hand on your chest and say thank you to your amazing heart! ❤️
Frequently asked questions
- How big is a child's heart?
- A heart is roughly the same size as the person's own clenched fist, so a child's heart is smaller than an adult's. It sits in the middle of the chest, leaning a little towards the left.
- Why does a heartbeat go 'lub-dub'?
- The 'lub-dub' is the sound of the heart's valves snapping shut as the muscle squeezes and then relaxes. One full 'lub-dub' is a single heartbeat that pushes blood out and then lets the heart fill again.
- What are the four chambers of the heart?
- The heart has four rooms called chambers: two on top (the left and right atria) that receive blood, and two on the bottom (the left and right ventricles) that pump blood out. Working together, they keep blood flowing in the right direction.
- Why does blood travel around the body?
- Blood works like a delivery truck, carrying oxygen and food (nutrients) to every cell and taking away waste the cells don't need. Without this constant delivery, the body's cells could not stay alive and healthy.
- What is a pulse and where can you feel it?
- A pulse is the little push you feel each time the heart squeezes and sends blood through your blood vessels. You can usually feel it on the inside of your wrist or on the side of your neck.
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