Circulatory System

How digested food from food pipe and absorbed food from body reaches every cell? Carbon dioxide from all body parts and other waste elements related to waste materials (kidney, lungs)? All there works are done by a pump (heart) and artery coming out and reaching there.

Blood flowing from there also helps in its functioning.

1. Heart

If you keep our hand at a slight left side you will hear or fell heart beat. This sounds like dhak dhak. This happens with every human heart beat.

Heart is a small (equal size of a fist), muscular organ and is established between the lungs in a cage. This is made up of tight muscles which work throughout life and does not get tired. 

Functions of Heart

The heart of a healthy adult person beats 60-80 times per minute (average 72 beats per minute). There are four chambers of heart - two in upper side right - left atria and bottom left - right ventricles. Right side of heart side has less oxygen blood and more carbon dioxide blood which reaches lungs. The pumped blood from lungs which has less amount of carbon dioxide and more oxygen reaches to the left side of heart where blood vessels take this blood to every cell of human body.

2. Blood Carrier Cells or Vessels

These are of three types: 

1. Arteries - these take blood containing oxygen to various parts of the body from heart. Their walls are thick and muscular.

2. Veins - they bring oxygen less blood from many parts of body to heart, then this blood is sent to lungs.

3. Cells - Arteries are divided in many branches and they join again together to form veins, this is a cage of veins. Minute blood cells in this system are called cells.


Blood is a shining red coloured liquid which flows in arteries and veins. Our blood has red blood cells and white blood cells. White blood cells are actually colourless, it also has very minute blood palattes.

Functions of Blood

  1. It takes oxygen from lungs to various parts of the body.
  2. It also takes absorbed food from intestine to many parts of whole body.
  3. Blood also takes waste material from body cells to kidney so that they come out as a part of urine.
  4. It also protects our body from infection.
  5. It also controls body temperature and keeps it static.
  6. If there is any injury or cut then blood clotting happens and stops the flowing of blood.