How does the heart pump blood around the body?
Short answer
The heart is a muscular pump with four chambers. The right side pumps deoxygenated blood to the lungs, where it picks up oxygen. The left side pumps oxygenated blood to the rest of the body. This is called a double circulatory system, because blood passes through the heart twice on each complete circuit.
Step by step
- Deoxygenated blood from the body enters the right atrium through the vena cava.
- It passes into the right ventricle, which pumps it through the pulmonary artery to the lungs.
- Oxygenated blood returns through the pulmonary vein to the left atrium.
- The left ventricle pumps it through the aorta to the rest of the body.
- Valves stop blood flowing backwards.
Worked example
Why is the left ventricle wall thicker?
- The left ventricle pumps blood all around the body
- It needs to create a higher pressure than the right ventricle, which only pumps to the lungs
- So it has a thicker muscular wall
Common mistakes
- Mixing up left and right. Diagrams show the heart as if you are facing the person, so their left is on your right.
- Saying arteries always carry oxygenated blood. The pulmonary artery carries deoxygenated blood.
- Forgetting the role of the valves.
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