Open Circulatory Systems
- In some insects and animal groups blood circulates in open spaces
- A simple heart pumps blood out into cavities surrounding the animals organs
- Substances can diffuse between the blood and cells
- When the heart muscle relaxes, blood is drawn from the cavity back into the heart through valved openings
Closed Circulatory Systems
Many animals, including vertebrates have a closed circulatory system in which blood is held in tubes or vessels.
Open, Closed, Double and Single circulatory systems.
Positives of a Closed Circulatory System
Negatives of a Closed Circulatory System
Since blood travels through narrow paths, blood travels faster and at a higher pressure so closed circulatory systems are more efficient. This makes it ideal for human beings
A negative of a closed circulatory system is if the blood is at too high of a pressure it can possibly damage the vessels.
Negatives of an Open Circulatory System
Negatives of an open circulatory system would be that enough blood does not flow around the body
However!
This is okay as open circulatory systems are usually found in insects and small animals with low surface area to volume ratio.
Advantages of a closed circulatory system over an open
Single Circulatory System
- In a fish, the blood travels from the heart to the gills, where it absorbs oxygen and releases carbon dioxide. It then flows from the gills to the organs and tissues in the rest of the body and back to the heart. There is just one circuit from the heart.
- A disadvantage is that it is less efficient as gill capillaries slow down the blood flow so the body receives blood at a low pressure as the fishes vessels cannot handle blood at a high pressure.
Double Circulatory System
- In a double circulatory system, the loop the goes to the lungs is called the pulmonary circuit.
- This is advantageous for animals as more blood could be pumped around to the body making the transport of food and nutrients efficient