Explain how blood circulates through the heart?

Firstly we need to know the anatomy of the heart. The heart is made up of four chambers, the top two are called Atria and the bottom two are called ventricles, the heart is also split up into a left side and a right side and the fun thing about anatomy is we switch round our left and our rights so the left side of the heart we call the right side and the right side we call the left side - this is just to do with the organisation of organs inside the body!
Deoxygenated blood flows in the veins and oxygenated blood flows in the arteries! So deoxygenated blood that has come from other parts of the body arrives via the vena cava vein into the right atrium, the blood then flows down into the right ventricle when the atria contract. The right ventricle then contracts forcing blood out of the ventricle into the pulmonary artery, this blood then travels in the artery to the lungs to drop off the carbon dioxide and pick up oxygen. The now oxygenated blood then flows from the lungs to the left atrium via the pulmonary vein, the atrium contracts and the blood is forced down into the left ventricle, the left ventricle will contract and blood will flow out into the Aorta artery and blood will be transferred to other parts of the body that are requiring the oxygen.