What are the components of the transport system in human beings? What are the functions of these components?


The transport system in humans is called the ‘ Circulatory System ’. The various organs of the circulatory system are Heart , Arteries , Veins and Capillaries

  • The heart acts like a pump, which pumps out oxygenated and deoxygenated blood .
  • Arteries , Veins and capillaries are the tubes through which the blood flows
  • Blood flows from the heart to the body in Arteries .
  • Veins carry blood from the body back to the heart .
  • Capillaries are small blood vessels with thin walls that allow oxygen and nutrients to diffuse through to the organs and cells , and waste diffuses back to the capillaries which combine to become veins.

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Human Heart :

  • Human heart is a four chambered structure having 2 atria (left and right) and 2 ventricles (left and right)
  • It is a double pump , which pumps blood around our body.
  • The left side of the heart (left atrium and left ventricle ) acts as one pump which pumps blood to the body , except the lungs.
  • The right side of the heart ( right atrium and right ventricle )only pumps blood into the lungs.
  • The left side of the heart is separated from the right side, by a partition called septum.
  • This separation is important to avoid mixing the oxygenated blood on the left side with the deoxygenated blood on the right.


Blood Vessels:

The blood vessels are of three types :

  Arteries : 

  • They carry blood from the heart to all parts of the body. 
  • Since they receive the blood directly from the heart which has a very high pressure , they are thick walled.
  • The main artery is called Aorta , carries oxygenated blood from the left ventricle to all parts of the body
  • The Pulmonary artery is connected to the right ventricle , which carries deoxygenated blood from the right ventricle to the lungs .

Veins : 

  • These blood vessels carry blood (deoxygenated) from the body back to the heart. 
  • They are thin walled because of the low pressure of the blood which flows in them
  • These have valves present in them which prevents backflow of blood.  
  • The main vein , called Vena Cava, is connected to the right atrium and carries deoxygenated blood from all parts, back to the heart
  • The pulmonary vein carries oxygenated blood from the lungs back to the heart.


Capillaries : 

  • These are thin walled, extremely narrow tubes which connect arteries to veins
  • The various dissolved substances like oxygen, food etc. present in blood pass through the capillaries. 
  • At the same time, the waste materials also enter the capillaries . Thus, an exchange takes place.
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CA Maninder Singh is a Chartered Accountant for the past 14 years and a teacher from the past 18 years. He teaches Science, Economics, Accounting and English at Teachoo