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Difference Between Single Circulation and Double Circulation

Last updated date: 04th Mar 2024
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Blood Circulation: Single Circulation and Double Circulation Examples

In order to differentiate between single circulation and double circulation, one must be aware of the blood and its circulation. Then, one can explain what is single circulation and double circulation.

Importance of Circulation: In order to sustain cell-level metabolism, body pH levels, osmotic pressure, stabilize body temperature, and defend against mechanical and microbiological damage, blood circulation is crucial for a healthy body. When the blood supply to particular internal areas is limited, issues arise.

It provides all of the organs and tissues with nutrition and oxygen. It also eliminates other waste products and carbon dioxide from the same locations. Once the blood is depleted of oxygen and filled with waste materials, it flows back to the heart.

What is Single Circulation and Double Circulation?

Single Circulation: The blood circulates around the body as it is pumped by the heart to the gills for oxygenation, then it returns to the heart. Single circulation is the name given to this method.

All fluids are transported into a cavity by blood vessels in an open circulatory system. The blood inside the cavity circulates freely throughout the body in all directions as the creature moves.

Examples of Single Circulation

Some species, such as fish, are known to have a single circulatory system. In addition, their hearts only contain two chambers rather of the typical two atria and two ventricles. As a result, single circulation has a substantial drawback since it delivers oxygen gradually, slowing down metabolism.

Double Circulation: Because it provides a reliable manner of flow, double circulation is a useful circulation technique. In order to circulate blood, the heart is the main organ. The primary distinction is that the blood travels along two different paths, one for oxygenated blood and another for deoxygenated blood. That is why it is called "double circulation." Most animals, including humans, have dual circulatory systems.

Components of Double Circulation

Systemic circulation

The left ventricles provide oxygenated blood to the tissue capillaries via systemic circulation.

Pulmonary circulation

Blood circulates from the right atrium to the left atrium in the pulmonary circulation.

Examples of Double Circulation

Blood circulates twice through the heart when there is double circulation. Most birds, mammals, certain reptiles, and a few fish species have it. Alligators, lungfish, crocodiles, birds, and mammals all have double circulations for this reason.

Differentiate Between Single Circulation and Double Circulation 



Single Circulation

Double Circulation



The flow of blood in one direction away from the heart. 

The flow of blood in two separate directions. 



Observed in animals with double-chambered hearts. 

Observed in animals with four-chambered hearts. 



Less efficient. 

More efficient.


Circulatory System

Open circulatory system.

Closed circulatory system. 


TRype of Blood

Only deoxygenated blood is pumped by the heart.

Both oxygenated and deoxygenated blood flow through arteries and veins due to the heart pump.



Seen in fishes.

Seen in mammals.


The aim of this article is to explain Single Circulation and Double circulation. The process of single circulation involves an open circulatory system in which the blood flows in only one direction and the same pathway is used to return the deoxygenated blood back to the heart. On the other hand, double circulation requires a closed circulatory system in which the blood flows through closed vessels like arteries and veins and there are separate pathways for the pure and impure blood. This prevents blood from mixing up and makes circulation more effective.

FAQs on Difference Between Single Circulation and Double Circulation

1. What are the characteristics of Single Circulation?

Below is an explanation of the major characteristics of single circulation.

  • For each circuit of the body, blood only makes one trip to the heart in single circulation.

  • Only animals with two or three chambers in their hearts have a single circulatory system.

  • There is just one circulatory system in aquatic creatures.

  • Only deoxygenated blood travels to the heart in single circulation.

It is evident that a single circulation does not have a separate transport route for oxygen-rich and oxygen-deficient blood, therefore, reducing the effectiveness of circulation.

2. What are the advantages of Double Circulation?

Double circulation supports the strict separation of blood that is oxygenated and deoxygenated. So, this circulation also improves physical efficiency by guaranteeing the body has a constant supply of oxygen. Animals are able to control their body temperatures in part because of this. In addition to double circulation, there is a third portal system to improve circulation. Blood that is high in carbon dioxide travels one way, while blood that is high in oxygen travels another.

3. What is Single Circulation and Double Circulation?

A "single circulation" is a circulation in which the heart only beats once throughout a single complete cycle of the body, moving blood via the gill capillaries and onto the capillaries in the body tissues.

A circulatory system known as double circulation involves the heart pumping blood through it twice during one complete cycle of the body. Most animals have two circulatory systems, including humans.

Compared to animals with single circulation, those with double circulation can control their body temperature and provide oxygen more efficiently.