1. Single circulation: In a blood circulation the blood passes through the heart only once. This type of circulation is called single circulation and the heart is called single circuit. Ex: Fish
2. Double circulation: Blood passes twice through the heart. Once between heart and lungs and second time from heart to body parts. Such circulation is called double circulation and the heart is called double circuit heart. Ex: Frog and other higher animals.
3.
| Single Circulation |
Double Circulation |
| 1. Found only in fishes. |
1. Found in amphibians, reptiles, birds and mammals. |
| 2. Blood passes only once through the heart to supply once to the body. |
2. Blood passes twice through the heart to supply once to the body. |
| 3. Only deoxygenated blood passes through the heart. |
3. Mixed blood (Oxygenated and deoxygenated) pass through the heart. |
| 4. It is less efficient in function as the oxygenated blood flows at a low pressure which decreases the rate of oxygen supply. |
4. It is most efficient in function as the blood flows at a higher pressure which increases the rate of oxygen supply. |
