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Learn About the Circulatory System for Kids
The circulatory system is made up of tubes that move blood all around the body. The word circulate means to move around. Some tubes are big and some are tiny. Think of the blood vessels as a bunch of connected roads and highways that carry traffic all around a city.
The heart pumps blood through these tubes, which are called blood vessels. Your heartbeat is the sound made by the heart pumping blood. The heart is actually a muscle. When the heart muscle relaxes blood flows in. When it tightens, blood flows out.
You need to take care of your heart by getting lots of exercise. Go outside to play everyday to keep your heart strong and healthy.
The Heart Has Four Chambers
The heart is divided into four parts called chambers. Think of chambers as tiny rooms. The chambers hold blood that is entering or leaving the heart. The two top chambers hold blood that is entering the heart. The bottom two chambers hold blood that is leaving the heart. The heart has valves that open and close to let blood in and out of the chambers. Valves are a little like doors.
Circulatory System Song
Why We Need Blood
The human body is made up of cells. These cells need nutrition and oxygen to make the energy we need to survive. Blood carries oxygen and nutrition to the cells. Blood must also carry waste away from the cells. Carbon dioxide is one type of waste that must be taken away and removed from the body. It is carried in the blood until it reaches the lungs. We can then breathe it out.
Other waste products carried by the blood go through organs called the liver and kidneys. This waste is removed in urine.
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Types of Blood Vessels
There are three types of blood vessels:
Arteries carry blood away from the heart. They are filled with oxygen-rich blood. The largest artery is called the aorta. Other arteries branch off from it. Think of the arteries as a tree with the aorta as the trunk and branches that get smaller and smaller attached to it. The arteries must carry oxygen-rich blood all around the body. Smaller blood vessels keep branching off until they reach the cells.
Tiny blood vessels called capillaries branch off the arteries into the cells. They deliver oxygen and nutrients and pick up waste. Then the blood travels back to the heart using blood vessels called veins.
The veins carry blood that is rich in carbon dioxide. The veins get larger the further away they are from the capillaries. As an example, small veins in the feet attach to larger veins in the legs. Blood from all the veins finally reaches two large veins that deliver it back to the heart. These two large veins have complicated names. They are called the superior vena cava and the inferior vena cava.
The heart then pumps this blood to the lungs to remove the carbon dioxide. Then the blood starts its journey around the body once more.