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Question: What are the main parts of the circulatory system? 



Answer: The main job of the Circulatory System is to get food and oxygen to all the cells in the body. It also carries away waste materials such as Carbon Dioxide produced in the body.

The Circulatory System is made up of three main parts:

The heart, the blood vessels and the blood. Sometimes the watery fluid called lymph and the vessels that carry it are considered to be part of the Circulatory System.

The Heart

The heart is a special pump that pumps the blood around the body.

When the blood enters the heart it is deoxygenated. The heart then pumps the deoxygenated blood to the lungs where it picks up some oxygen. The blood is now oxygenated. This oxygenated blood travels back to the heart. The heart now pumps the oxygenated blood around the body so that every cell gets a supply of vital oxygen.

This sequence is repeated over and over again.

Blood Vessels

Arteries, capillaries and veins are blood vessels.

Arteries carry high pressure blood which is full of oxygen ( this is called oxygenated blood) away from the heart.

Veins carry low pressure blood back to the heart. The blood in veins has had the oxygen removed in the body (this is called deoxygenated blood).

Capillaries - have very thin walls which allow food, oxygen and waste to pass through.

The Blood

There are four parts to the blood:

1: Red Cells - these contain a substance called haemoglobin which carries oxygen in the blood.

2: White Cells - these have the job of killing off invading microbes.

3: Plasma - this is a liquid which contains salts, sugars and proteins.

4: Platelets - these are bits of dead cells that clot the blood. 




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