The Circulatory System focuses on sending oxygen and nutrients to different parts of the body. The heart, the blood, and the blood vessels all work together to serve the cells of the human body. Using the network of arteries, capillaries, and veins, the blood carries carbon dioxide to the lungs and picks up oxygen.  

     The heart is the main part of the circulatory system. The heart pumps our blood around the body. It sits inside the chest slightly to the left side of the body in front of the lungs. The heart has four chambers, with a flow of the blood going in one direction due to the presence of heart valves. The sound of heartbeats is actually the contractions of the chambers.

The right upper chamber of the heart, the right atrium, takes in blood full of carbon dioxide but no oxygen. The blood is then squeezed down into the right lower chamber, the right ventricle, and taken by an artery to the lungs where the carbon dioxide is exchanged with oxygen.

The oxygenated blood is taken to the upper left side, the left atrium. It is pumped into the left lower chamber, the left ventricle, and then into the aorta, an artery. The blood starts its journey around the body once more.