Heart, arteries, veins and lungs are the major component of the circulatory system.
The heart has four chambers. Two atria and two ventricles.
The arteries carry oxygenated blood from the heart to the different parts of the body.
The deoxygenated blood is returned back to the heart via veins.
Lungs receive the deoxygenated blood from the heart via pulmonary artery. It oxygenates the blood and returns to the heart by pulmonary veins.
Circulation :
The right atria receive the deoxygenated blood by the vena cava (collection of veins).
The atria contracts and pumps the blood to the right ventricle.
The right ventricle pumps the blood via pulmonary arteries to lungs for oxygenation.
The oxygenated blood from the lungs moves to the heart via pulmonary veins.
From pulmonary veins, blood enters in the left atrium and then left ventricle.
From left ventricle, blood goes to aorta which comes out of the heart and breaks into arterioles and distribute the oxygenated blood to different organs.