Why big bodies need a pump
Your heart is about as big as your fist. It pushes blood to every cell.
- The heart has a right side and a left side.
- Oxygen-poor blood from the body enters the right side.
- The right side pumps it to the lungs.
- Oxygen-rich blood returns from the lungs to the left side.
- The left side pumps it to the body.
- Blood passes through the heart twice in one round.
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Blood is back from the body. Tap the stops in order.
The rule
Blood carries food, oxygen and wastes. The heart is the pump that pushes blood round the body. Arteries carry blood away from the heart. Veins carry blood back to the heart.
Each side of the heart has two chambers. A chamber is a hollow space in the heart. The upper one is the atrium. The lower one is the ventricle.
Blood goes through the heart twice in one round of the body. This is double circulation. The right side sends blood to the lungs. The left side sends it to the body.
The heart keeps oxygen-rich and oxygen-poor blood apart. So cells get plenty of oxygen. Birds and mammals keep their bodies warm. That takes much energy. Making that energy needs much oxygen. So birds and mammals gain much from a heart with separate sides.
Watch out!
An artery is not always oxygen-rich. It is defined by direction, away from the heart. The artery to the lungs carries oxygen-poor blood.