Introduction to the circulatory system
Your circulatory system has three main parts:
- Heart which pumps blood around your body.
- Blood vessels which carry the blood.
- Blood.
Watch: The circulatory system
Look! The heart is working hard to pump blood around the body.
The heart is a pump, and the blood goes round, and round, and round all the time.
And why does it do that?
Why can't it just have a rest?
Well, the blood has to be kept moving around all the time because it's the body's delivery system.
Every possible part of the body has to be supplied with oxygen and food and water, and the veins and arteries are like roads going all the way through your body with the blood cells like delivery vans.
The body is all the time shouting out:Over here! Delivery needed! I need oxygen!
I need nutrients!
That means that the vans are very busy indeed, all the time.
So it's a good job we've got the circulatory system to transport nutrients, water and oxygen to the entire body.
Right come on heart, back to work. Quick!
The heart
Your heart is a very strong muscle which contracts (gets smaller) and relaxes to pump blood around your body. A heart beat varies from person to person - for an average person it beats 60-100 times a minute. You feel this when you feel your
This is the journey that blood takes:
Watch: How the heart pumps blood
Check out the muscular heart and its extraordinary pumps.
Watch: Blood vessels
Blood vessels carry blood. There are three types:
- Arteries carry blood away from the heart.
- Veins carry blood back to the heart.
- Capillaries are tiny vessels which carry blood into your organs and tissues.
Watch and learn about the magnificent blood vessels in your body.
Inside you, there is an amazing network of blood vessels, the tubes that carry blood all around your body.
Every part of the body needs oxygen, food and water.
The blood vessels are a bit like roads going around a city with deliveries, while the veins take away waste.
Do you know how many roads there are in just one person?
Well, if we could take them all apart and lay each section out in a straight line, it would go all the way around the world鈥wice!
Of course, you could only drive on it in a very very very small car.
Watch: Blood
Blood is made from four parts:
- Red blood cells which transport oxygen.
- White blood cells which protect against disease.
- Blood platelets which help the blood to clot and form scabs to repair a cut.
- Plasma which is a yellowy liquid that carries these cells and important nutrients around your body.
There are different types of blood cells with different jobs.
Narrator: Blood gets around our bodies through a system of blood vessels.
To picture the blood vessels, imagine a busy network of roads.
And those roads are always full of little vans which are busy making deliveries and rubbish trucks picking up rubbish and police cars looking out for intruders.
Police: We have a suspect heading full speed towards the stomach. Require immediate backup!
Narrator: Your blood has different cells with different jobs.
Some cells do repairs if you get a cut.
Red blood cells deliver oxygen and take away rubbish.
And your white blood cells are like police looking for germs.
There's a lot going on inside you!
Watch: Circulation summary
To extend your learning, have a look at
This video recaps all the key learning points about the circulatory system.
Here's what you need to know about the circulatory system.
Activity 1: Fill in the gaps
Activity 2: Circulatory systems quiz
Activity 3: Create a booklet
Create a booklet or leaflet explaining each part and the role it plays within the circulatory system.
Teaching resources
Looking for more teaching resources to share with your students? This short film explains how the heart and circulatory system work, taking a close look at the four chambers, two sides, and the valves of the heart.
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