Biology
Breathing & circulation
Every breath and every heartbeat supplies your body. This is how the lungs and heart work together.
What you need first
Hold your breath for a moment and you feel right away how important breathing is. Your body needs oxygen, in every single cell. Two systems make sure it reaches everywhere: the lungs and the heart with the blood.
The lungs exchange gases
When you breathe in, air flows into your two lungs. From this air the lungs take up oxygen and pass it to the blood. At the same time the blood hands back to the lungs. When you breathe out, this carbon dioxide is carried outside.
The heart pumps blood through the body, carrying oxygen and nutrients to every cell.
The heart as a pump
The heart is a strong muscle, about the size of your fist. Inside it is divided into four chambers: two atria take in the arriving blood, two ventricles squeeze together with every beat and push the blood along. In a simple picture you can remember two : one leads through the lungs, the other through the whole rest of the body.
Blood as a transport
The blood is like a delivery service that never takes a break. It brings oxygen and nutrients to every cell and takes waste away again, including the carbon dioxide that forms in the cells and is handed over in the lungs. Its red colour comes from the red blood pigment haemoglobin, which holds on to the oxygen and carries it through the body.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
Which gas do the lungs take up from the air you breathe in?
Where does the red colour of the blood come from?
How many chambers does the heart have inside, counting atria and ventricles together?
Put the path of oxygen in the right order, from breathing in to the cell.
- 1The heart pumps the oxygen-rich blood through the body.
- 2The oxygen reaches the individual cells.
- 3The lungs hand the oxygen over to the blood.
- 4You breathe fresh air into the lungs.
How many lungs does a human have?
Match each part of the system to its job.
Where this leads