Open Circulatory System vs. Closed Circulatory System

Difference Between Open Circulatory System and Closed Circulatory System

Circulatory system is responsible for maintaining the functions of a body. It is supplies nutrients and oxygen to different parts of the body and keeps them functional. It also carries waste products from cells to the excretory system. There are two types of circulatory systems in complex organisms like human beings and animals.

Close circulatory system has systematic and pulmonary circulation and these are two main functions. In pulmonary circulation the blood from the entire body is taken to lungs so that it can be charged with fresh oxygen and then systematic circulation takes this blood from lungs and circulates it to the cells and organs n the entire body. This circulation is done through veins and the blood is circulated at very high pressure. This system pumps blood faster and this is why it is suitable for the animals with high metabolic rate. Animals with close circulatory system are active and their digestion is fast and so is the process of elimination of waste from the body.

In open circulatory system the heart pumps blood in the body cavities. Blood vessels carry blood from these cavities and circulate it throughout the body. Animals with open circulatory system have more blood because the blood pressure remains low due to absence of arteries. Open circulatory system is good for smaller animals which have lower rate of metabolism because it consumes less energy. Small and lesser active animals do not need that much of oxygen and this is why the longer time taken by oxygen to reach to the cells hardly affects them. The low blood pressure slows down the process of circulation.

Here are some of the other differences between these two systems:

  • Blood does not leave the network of blood vessels in case of closed circulatory system. In open system the blood gets pumped into the circulatory system. The blood pools around the tissues and organs and is again pumped into the circulatory system.
  • The blood in the organs is changed in every cycle with fresh blood in case of open system while this does not happen in closed system.
  • In open system there is no risk of high blood pressure because there are no veins for carrying blood and the animals which have open system have more blood than the animals which have close system.


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