The Chambers
The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle.
The left ventricle receives blood from the left atrium and pumps it to the body through the aorta.
The right atrium receives oxygen-poor blood from superior and inferior vena cavae and pumps it to the right ventricle.
The right ventricle receives blood from the right atrium and pumps it to the lungs through the left pulmonary artery,
Blood Flow
Deoxygenated blood flows from the superior and inferior vena cavae into the right atrium. The right atrium pumps deoxygenated blood to the right ventricle, which pumps deoxygenated blood to the lungs. Specifically, the right pulmonary artery carries the deoxygenated blood from the right ventricle to the lungs. The lungs oxygenate the the formerly deoxygenated blood. The newly oxygenated blood flows to the left pulmonary veins, These veins take the oxygenated blood to the left atrium. The left atrium pumps oxygenated blood into the left ventricle. The left ventricle pumps the oxygenated blood into the aorta for transport.
The Heart Conduction System
The atria contract and pump blood but the ventricles are still relaxed and filled with blood. The sinoatrial node generates an electrical impulse, which travels to the atrioventrical node. The atrioventricular node delays the impulse by .1 second before it is transmitted to the Purkinje fibers, The impulse is delayed because during the .1 second, the atria are stimulated to contract before the ventricles can contract. The Purkinje fibers cause the ventricles to contract while the atria are at diastole.
Open and Closed Circulatory Systems
In a closed circulatory system, blood flows through enclosed vessels throughout an organism's body. In an open circulatory system, blood flows freely and is not trapped inside vessels.
Diastole and Systole
Diastole: Relaxation phase
Systole: Contraction phase
Veins and Arteries
Veins carry blood to the heart.
Arteries carry blood away from the heart.
Valves
Tricuspid valve prevents backflow of blood between the left atrium and the left ventricle.
Bicuspid/mitral valve prevents backflow of blood between the right atrium and the right ventricle.