The quick answer
Your heart is a strong muscle that works like a pump. Every time it squeezes, it pushes blood through tubes to every part of your body. The blood carries oxygen and food that your body needs to keep going.
TankiRanki, when I put my hand on my chest, I can feel thump, thump, thump. What is my heart doing in there?
RankiIt’s pumping, all day and all night, without a single break. Let’s find out how it works!
A muscle about the size of your fist
Make a fist. Your heart is about that size, and it grows as you grow. It sits in your chest, a little to the left of the middle, safe behind your ribs.
Your heart is a muscle, like the muscles in your arms and legs. But it never gets tired the way your legs do. It keeps squeezing and relaxing your whole life, even while you sleep. Each squeeze is one heartbeat.
Blood is a delivery service
Your heart pumps blood, and blood is like a delivery van. It carries oxygen from the air you breathe and food from the meals you eat. It drops them off everywhere, from your brain to your toes.
On the way back, blood collects waste that your body does not need. Some of this waste is a gas, and you breathe it out with every breath.
Four rooms and little doors
Inside, your heart has four rooms called . There are two at the top and two at the bottom. The right side sends blood to your lungs to pick up fresh oxygen. The left side pumps that fresh blood out to the rest of your body.
Between the rooms are little flaps called . They work like doors that only open one way, so the blood cannot flow backwards. When the valves snap shut, they make the sound of your heartbeat: lub dub, lub dub.
TankiSo the thump I feel is really tiny doors snapping shut? That’s brilliant.
RankiYes! Doctors listen to it with a stethoscope. That’s a tool with a long tube and two earpieces.
A map of tubes
Blood travels through tubes called . There are three main kinds:
- carry blood away from the heart.
- carry blood back to the heart.
- are tiny tubes, thinner than a hair, that reach every part of your body.
Each time your heart beats, it sends a push of blood through your arteries. You can feel this push in some places, like your wrist and your neck. It is called your .
When you are resting, a child’s heart usually beats about 70 to 100 times a minute. When you run or jump, your muscles need more oxygen. So your heart beats faster to deliver it. Moving and playing every day helps to keep your heart strong.
Try it
Find your pulse
You need
What to do
- Sit still for a minute.
- Put two fingers on the inside of your wrist, just below your thumb.
- Press gently until you feel a little beat.
- Count the beats while someone times 1 minute. Write the number down.
- Now jump on the spot for 1 minute, then count again. What has changed?
TankiSo my heart is a pump, a delivery boss and a drummer, all in one. Busy little muscle.
RankiAnd it’s working for you every second. Give it a good run around today, and it gets even stronger.
Big words
- chambers
- The four rooms inside your heart.
- valves
- Little flaps in the heart that only let blood flow one way.
- stethoscope
- A tool doctors use to listen to your heart.
- blood vessels
- Tubes that carry blood all around your body.
- arteries
- Blood vessels that carry blood away from the heart.
- veins
- Blood vessels that carry blood back to the heart.
- capillaries
- The tiniest blood vessels, thinner than a hair.
- pulse
- The beat you can feel when your heart pushes blood through your arteries.
Quick quiz
1. About how big is your heart?
Your heart is about as big as your fist, and it grows as you grow.
2. What makes the lub dub sound of your heartbeat?
The sound comes from the little valves closing inside your heart.
3. Which blood vessels carry blood away from the heart?
Arteries carry blood away from the heart, and veins bring it back.
For parents and teachers
The heart pumps blood in two loops: the right side sends it to the lungs and back, the left side sends it around the rest of the body. Resting heart rates vary from child to child, so the pulse activity is about noticing the change after exercise, not about reaching a particular number. To go further, try listening to each other’s heartbeat through a cardboard tube held against the chest.
Pictures marked “AI generated” were made with AI tools. Ranki and Tanki are AI generated characters. Found a mistake? Write to info@pr-geo.com and we will fix it.
