Closed Circulatory System – Class 11 | Chapter – 18 | Biology Short Notes Series PDF

Closed Circulatory System: The circulatory system is one of the transport systems through which nutrients, gases, and other molecules are transported within the body of animals. There are two major types of circulatory systems: the open circulatory system and the closed circulatory system.


In a closed circulatory system, the heart pumps the blood directly into the blood vessels, where it flows through the closed vessels like veins and capillaries. The closed circulatory system does not feed the organs and the tissues directly with the blood but flows through a closed channel of blood vessels. 

The exchange of gases is usually done by the capillaries between the blood and the tissues of the body. The common examples of the closed circulatory system are vertebrates including humans. 

Humans have a developed cardiovascular system to circulate blood throughout their bodies, besides having a developed lymphatic system to circulate lymph through the body.

Exchange Of Gases In Closed Circulatory System

The blood flows through the capillaries in the lungs where the oxygen gas diffuses into the bloodstream through the tiny membranes. The oxygenated blood is thus transported to the heart from where it gets away through arteries. 

Meanwhile, the body uses oxygen in metabolism and creates carbon dioxide. The deoxygenated blood is taken back to the heart through veins where it goes through the same process again.

Components of Closed Circulatory System

Components of a closed circulatory system are specified below: 

  • Heart: The heart is the main part of the circulatory system. It is a fleshy organ made up of special cardiac muscles and is around the size of a closed fist. It lies in the center of the chest, slightly left of the center. This organ is protected by the rib cage. The heart is the central part of the circulatory system in living organisms. 
  • Arteries: The heart pumps the purified oxygen-rich blood in the arteries that take the blood to the rest of the body.
  • Veins: The deoxygenated blood from all over the body is taken to the heart by veins. This impure blood goes through the lungs to oxygenate itself.
  • Blood: Blood is a fluid that carries all the material within it to transport it to the whole body. The material includes hormonesnutrients, and oxygen

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By Team Learning Mantras