Circulatory System Byju pdf

Circulatory system

"Circulation means" anything which moves around.

The system that contains the heart and the blood vessels and moves blood throughout the body. This system helps tissues get enough oxygen and nutrients, and it helps them get rid of waste products.

Circulatory system is of two types 

1. open circulatory system-  where there is no blood vessels involved ex- cockroach and

2. closed circulatory system like human being where blood vessels supplies the blood to other organs.

This system consists 3 organs

1. blood 

2.blood vessels 

And most important

3. heart

Blood vessels are further divided into two parts 

1. arteries

2.veins

The discovery of blood circulation system was done by William Harvey.

Points to remember:

Biological term of the heart is ‘Cardio’.

Doctor Who study heart is called cardiologist our heart consist four Chambers 

And is of a size of closed fist

Atrium are the upper parts and ventricles are there a lower parts heart.

It remains safe in the pericardial membrane.

Its weight is approximately 300 grams for male and 250 gms for female.

The human heart is a four chamber heart.

In one cycle heart pumps 70ml blood.

The major function of the heart is Pumping of blood/circulation of blood.

The heartbeat of a normal human being is 72 beats/minute.

It is a pumping organ works in a rhythmic cyclic manner with systole(shrinkage for .3sec)  and diastole (expansion for .5 sec).

The vein is the vessels which carry the blood from the body towards the heart.

The vein contains impure blood i.e. carbon dioxide mixed blood.

Pulmonary vein is the exception which always carries pureblood.

Pulmonary vein carries the blood from the lungs to the left atrium.

The artery is the vessel which carries the blood from the heart towards the body.

Artery contains pure blood i.e. oxygen mixed blood.

But Pulmonary arteries are the exception which always carries the impure blood or 

deoxygenated blood.

The pulmonary artery carries the blood from the right ventricle to the lungs.

In the right part of the heart, there remains impure blood i.e. carbon dioxide mixed blood and in 

the left part of the heart there remains pure blood i.e. oxygen mixed blood.

The artery carrying blood to the muscles of the heart is called coronary arteries. Any type of 

hindrance in it causes a heart attack.

Covering of heart is called as Pericardium.

The course of circulation:

Along with a closed circulatory system, Mammals have double circulation.which means blood 

has to cross two times from heart before circulating throughout the body.

The right atrium receives impure blood from the body which goes into the right ventricle. From 

here the blood went into pulmonary artery which sends it to the lung for purification. After 

purification, it is collected by a pulmonary vein which brings it back to the heart in the left 

atrium. From the atrium, it vents into the left ventricle. Now, this purified blood goes into the 

aorta for different organ of the body. This circulation is done is a cardiac cycle.

Biggest heart blue whale 280 to 300 kg