Science
What does the heart do?
Quick answer
The heart is a muscle about the size of your fist that pumps blood around your body, carrying oxygen and food to every cell and taking waste away.
In one sentence
Your heart is a strong muscle that pumps blood around your body all day and night, delivering oxygen and food to every part of you.
Explained
Every cell in your body needs oxygen and food to stay alive. Blood is the delivery service, and your heart is the pump that keeps it moving.
Your heart sits in the middle of your chest, behind your breastbone and between your lungs, tilted a little to the left. It is about the size of your fist and is made of a special muscle that never gets tired the way your arm muscles do.
Inside, the heart has four chambers. Think of it as two pumps side by side:
- The right side sends blood to the lungs to pick up oxygen and drop off carbon dioxide.
- The left side pumps the fresh, oxygen-rich blood out to the rest of the body.
Blood travels through tubes called blood vessels. Arteries carry blood away from the heart. Veins bring it back. Tiny capillaries link them, so thin that blood cells pass through in single file. Valves inside the heart work like one-way doors so blood cannot flow backwards. The "lub-dub" sound of a heartbeat is the sound of those valves closing.
When you rest, an adult's heart usually beats between 60 and 100 times a minute. Children's hearts usually beat a bit faster. When you exercise, your heart speeds up to send more oxygen to your muscles.
Examples
- Find your pulse: press two fingers gently on the inside of your wrist or the side of your neck. Each throb is one heartbeat.
- Compare: count your pulse for 15 seconds sitting still, then after a minute of star jumps. Multiply each by 4 to get beats per minute.
- Listen: with a cardboard tube held against a friend's chest, you may hear the lub-dub.
Common mistakes
- "Blood in veins is blue." Blood is always red. It is darker red with less oxygen; veins look blue because of how light passes through skin.
- "The heart is shaped like a love heart." A real heart is more like a rounded cone or a large pear.
- "Your heart is on the left." It is near the centre of your chest, just tilted to the left.
Quick quiz
The heart
Check what you know with 4 quick questions.
Question 1 of 4
What does the heart pump around the body?
Practise it
Try it
Read how the heart and lungs team up, and try the story My Heart Is a Drummer with younger children.
Heart and circulation activities
For grown-ups
Related topics
Lungs
The lungs are two spongy organs in your chest that take oxygen from the air into your blood and remove carbon dioxide when you breathe out.
The human body
The human body is made of trillions of cells that form organs, such as the heart, lungs and brain. Organs work together in systems that keep you moving, breathing, eating and thinking.
Cells
A cell is the smallest living unit. Every living thing is made of one or more cells, each with a membrane, cytoplasm and, in plants and animals, a nucleus that controls it.
Healthy eating
Healthy eating means eating a variety of foods from all the main food groups, with plenty of fruit and vegetables and water to drink, so your body gets everything it needs to grow.
Skeleton
The skeleton is the frame of bones inside your body. It holds you up, protects soft organs like the brain and heart, and works with muscles so you can move. Adults have 206 bones.
Digestive system
The digestive system is the long tube and organs that break food down into tiny pieces your body can absorb for energy and growth, then get rid of what is left as waste.