Our pump-the heart.
The heart is a muscular organ which isas big as our fist Because both oxygen and carbon dicocide have to be transported by the blood, the heart has diferent chambers to prevent the Vogen rich blood from mixing with the Bloed containing carbon dioxide. The carbon dioxide-nch blood has to reneh The lungs for the carbon dioxide to be mood and the oxygenated blood from the lungs his to be brought back to the heart. This oxygen-rich blood is then to the rest of the body.
We can follow this process step by Mirp Oxygen-rich blood from the tongs conies to the flon walled upper chamber of the heart on the left, she left atrium. The left atrium relaxes when it is collecting this blood, It then contracts, while the nest chamber. the left ventricle. Relaxes, so that the blood is transferred to . When the muscular left ventriclessntracts to its turn, the blood is pumped out to the body De oxygenated blood comes from the body to the upper chamber on the night, the right artium, as it relaxes. As the right atrium contracts the corresponding lower chamber, the right ventricle, dilates This transfers blood to the right ventricle, which in tum pumps it to the fungs for oxygenation Since ventricles have to pump blood into various orangans, they have thicker muscular walls than the atto le Valves ensure that blood does nuts backwards when the atria or ventricles contract.