How Much Blood Circulates in the Human Body ?

We all know that blood is the fluid of life because it carries oxygen which is the essential component needed for the human body. We also know that the blood is composed of plasma, blood cells and platelets, but do we know that how much blood is being pumped in the body ? Also what is the system called which circulates the blood to our whole body ? Let's find out.

How much blood circulates in the human body ?

The amount of blood that circulates in the whole body is 5 litres per systole and diastole. Systole is when the heart has pumped the blood. Diastole is when the heart is in a relaxed state after pumping. The blood in our body occupies 8% of the total body weight.

The system which circulates the blood to all the parts of our body is called the circulatory system or cardiovascular system or vascular system. The circulatory system consist of the heart, pulmonary and the systemic circulation.

The systemic circulation functions in two parts: Marcocirculation and Microcirculation.
  1. Macrocirculation - This circulates the blood from the heart to the organs and back to the heart. 
  2. Microcirculation - This circulates the blood through the smallest vessels to the tissues and other organs except the cornea.

Circulatory system:

The circulatory system is a network from where the blood is transferred from the heart to the rest of the body. Apart from carrying blood to all the parts of our body it also removes the waste products that the blood carries which are not needed.

It is also responsible for flowing blood nutrients, oxygen, hormones to the cells and back from them and other gases. The circulatory system consists of heart, lungs, arteries, veins, coronary and portal vessel.


The heart is located between the lungs in the middle of the chest. It is divided into 4 chambers: upper left and right atria and lower left and right ventricles. The blood which has been oxygenated is flown through the valves which prevents the blood from flowing back to the heart. 


The deoxygenated blood is entered from the right atrium through the superior and inferior vena cava. Once the blood is received in the heart it is passed on to the right ventricle from where it is being carried to the lungs for removal of carbon dioxide. The blood which was received by the lungs has now been oxygenated and is send to the left atrium and then to the left ventricle. The arota finally pumps out the oxygenated blood though the help of the blood vessels.


Lungs are air filled and spongy organs which are located on each side of the chest. 

The lungs receive the blood for oxygenation and the deoxygenated blood is sent to the alveoli to be exhaled out. The lungs exchange carbon dioxide and oxygenates the blood taking it away from the right ventricle.


The artery is a part of the blood vessel. They carry oxygenated blood to the tissues. The pulmonary artery does no carry the oxygenated blood instead it carries the deoxygenated blood to the lungs so it's an exception. Well, after from taking blood to various tissues of the body, the arteries also help to maintain the pH of the blood and circulates proteins and cells of the immune system



The largest vein in the body is the vena cava and smallest veins are called venules. The veins carry the blood which is remaining back to the heart but now it is blue in colour. The heart will collect more oxygen and prepare to be pumped back out through the arteries. The veins are spread throughout the body. 

 Veins throughout the whole body
Veins throughout the whole body

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