Double Circulatory Systems
Biology: Cambridge International GCSE Supplement, topic 9.1.2
Double Circulatory System
The circulatory system of mammals has three key components: blood vessels, blood and the heart. It is called a double circulatory system because blood passes through the heart twice per circuit:
Blood enters the heart
- Deoxygenated blood from the body enters the into the right atrium of the heart.
Blood pumped to lungs
- This deoxygenated blood is pumped out of the heart and towards the lungs by the right ventricle.
Lungs oxygenate the blood
- At the lungs, the deoxygenated blood exchanges carbon dioxide for oxygen. This is how it becomes oxygenated (contains oxygen).
Blood returns to heart
- Oxygenated blood returns to the left atrium of the heart.
Blood pumped to the body
- This oxygenated blood is pumped out of the heart and to the body by the left ventricle.
Blood returns to the heart
- The oxygenated blood gives its oxygen to body cells in exchange for carbon dioxide.
- The blood becomes deoxygenated and returns to the heart.
Test yourself on Double Circulatory Systems
Why is the mammalian circulatory system called a double circulatory system?
Which chamber of the heart receives deoxygenated blood from the body first?
The Double Circulatory System
What would happen if blood did not pass through the heart twice in one circuit?