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Single vs Double Circulation: Why Body Plan Follows Metabolic Demand
- Circulatory systems vary with an animal's metabolic demands and environment.
- Bony fish use a single circulation, while mammals use a double circulation that sustains a much more active lifestyle.
Single Circulation in Bony Fish: Blood Passes Through the Heart Once
Definition
Single circulation
A type of circulatory system in which blood flows through the heart once per complete circuit.
- In bony fish, blood passes through the heart only once per complete circuit.
- The heart has just one atrium and one ventricle.
- Blood Flow Sequence in Bony Fish
- Oxygen-poor blood from the body returns to the heart, entering the atrium and then the ventricle.
- The ventricle pumps blood to the gills, where it picks up oxygen and releases carbon dioxide.
- Oxygen-rich blood then flows from the gills straight to the rest of the body.
- Finally the blood returns to the heart to complete the single loop.
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- B3.2.14 Differences between circulation of bony fish and of mammals (HL)
- B3.2.15 Adaptations of the mammalian heart for delivering pressurized blood to the arteries (HL)
- B3.2.16 Stages in the cardiac cycle (HL)