You are here: Life > LET'S EXPLORE The human body > What does the heart do?

What does the heart do?

Blood containing fresh oxygen (red) travels from the lungs to the heart through the pulmonary veins (1). At the same time, blood...Read More >>Blood containing fresh oxygen (red) travels from the lungs to the heart through the pulmonary veins (1). At the same time, blood with very little oxygen left in it (blue) returns to the heart along veins from the body (2). The heart pumps the fresh blood to the rest of the body (3) and the exhausted blood to the lungs via the pulmonary artery, to get rid of the carbon dioxide and take in fresh oxygen (4).The heart lies at the centre of what is called the circulatory system. This includes the lungs and the network of blood vessels that reaches to all parts of the body. The heart sucks in oxygen-filled blood from the lungs, then pumps it around the body through arteries. Meanwhile, veins bring used-up blood, containing carbon dioxide, back to the heart. The heart sends this blood to the lungs to get rid of the carbon dioxide and take in fresh oxygen. The cycle begins again.


Blood enters the heart (top) and is squeezed out (above).

How the heart works

About the size of your fist, the heart is a powerful pump. As the muscles of the heart relax, blood enters its various “chambers”. Oxygen-filled blood from the lungs fills the red chambers in the diagram (left). At the same time, carbon-dioxide-filled blood from the rest of the body enters the blue chambers. 

The first heartbeat in a human being happens in the fourth week of pregnancy.

Q-files now has new sections specially written for younger readers. They are: Living world, Earth, Science, Human body, Prehistoric life, Space, History, Geography and Technology.


Find the answer