My Body: Heart and Blood

Your heart is a muscle.
It works like a pump.
It sends blood around inside your body.
Blood takes good things to parts of your body.
It takes away waste.

The movement of the heart and blood is called the cardiovascular (say car-dee-oh-vass-cue-luh) system of the human body. What is blood?

The heart is a muscle inside a person's chest. Your heart is about the size of your fist. It pumps blood so that the blood moves to every part of the body. Blood is red and watery and helps keep people well. Blood keeps moving all through your body all the time.

Blood goes out of the heart in tubes, or vessels, called arteries (say ah-ter-reez). The blood takes oxygen and nutrients to all parts of the body and takes away waste. It goes back to the lungs through tubes, or vessels, called veins (say vanes). The lungs put air back into the blood (it becomes oxygenated), before it goes to the heart again to be pumped out through the arteries and round the body again.Oxygenated blood is pumped out of the aorta at about 1.6 km per hour. It takes about 20 seconds for blood to circulate around your entire body.

Sections of the Heart
The human heart consists of four sections, called chambers. There are two on each side of the heart, two on top and two underneath. On top there is a left atrium and a right
atrium (say ay-tree-um). The two together are called atria (ay-tree-uh). These fill with blood that is returning from the body and lungs. Underneath the atria are the left and right ventricles. They pump out the blood to go to the body and lungs. The left and right sides of the heart are separated by a thick wall of muscle called a septum.
Click here to see how the heart works: http://www.neok12.com/php/watch.php?v=zX5d7d0e41705968036a4351&t=Circulatory-System
(Note: 5 quarts = 4.7 litres)

Pulse and Blood Pressure
Before each beat, the heart fills with blood. Then the muscle squeezes and pushes the blood out. Your heart does this constantly. You can feel your heart beating. It is called a
pulse. A doctor or nurse feels your pulse on your wrist, but it can be felt at other places too. Your heart beats about 100 000 times each day.

Sometimes a doctor or nurse needs to check that a person's heart is beating strongly and at the right speed. This is called blood pressure.
A machine measures the person's blood pressure.

Blood Types
There are different types of blood. Most people have the blood called A or O, and other types are more rare.

If a person is hurt or ill and loses a lot of blood, they urgently need more blood to be put inside their body. This is called a blood transfusion. A bag of the same type of blood is attached to a rack and a tube are attached to it. The other end of the tube is put inside a vein in the person's arm. The blood drips slowly from the bag down the tube.

Extra blood is kept at a Blood Bank. People go there to give blood. Nurses take the blood from a vein. People who give blood are helping save other people's lives. It is safe to give a little blood because a healty person's bone marrow makes more blood.

The blood is kept in special bags and kept in special storage for times when it is needed.

In the picture you can see a bag of "A Positive" blood at a Blood Bank


To read more about the cardiovascular system go here
http://www.innerbody.com/htm/body.html
http://www.mplsheartfoundation.org/kids/
http://kidshealth.org/teen/your_body/body_basics/heart.html

Go here for some videos of the human circulatory system

http://www.neok12.com/php/watch.php?v=zX0a0c66477f4a72445c0e63&t=Circulatory-System

There are different types of blood vessels moving blood in your body:
http://www.neok12.com/php/watch.php?v=zX7152787e557e671b564073&t=Circulatory-System


If you use any part of this, write the source in your bibliography like this:
Sydenham, S. & Thomas, R. Heart and Blood [Online] www.kidcyber.com.au (2004)


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