Which chamber of the heart receives oxygenated blood from the lungs?

Choice A rationale The left ventricle is the chamber responsible for pumping oxygenated blood out to the systemic circulation via the aorta. While it contains oxygenated blood, it does not receive it directly from the lungs. Instead, it receives blood from the left atrium through the mitral valve. The left ventricle has the thickest muscular wall of all four chambers because it must generate enough pressure to overcome the systemic vascular resistance of the entire body. Choice B rationale The right atrium receives deoxygenated blood from the systemic circulation through the superior and inferior vena cava, as well as the coronary sinus. This blood is high in carbon dioxide and low in oxygen. From the right atrium, blood passes through the tricuspid valve into the right ventricle. Therefore, this chamber is part of the "blue" side of the heart and is not the recipient of freshly oxygenated blood from the pulmonary veins. Choice C rationale The left atrium is the specific chamber that receives oxygenated blood from the lungs via the four pulmonary veins. After gas exchange occurs in the pulmonary capillaries, where carbon dioxide is released and oxygen is absorbed, the blood returns to the heart. This marks the end of the pulmonary circulation circuit. The left atrium acts as a holding chamber before the oxygen-rich blood is moved into the left ventricle for systemic distribution. Choice D rationale The right ventricle receives deoxygenated blood from the right atrium and pumps it into the pulmonary artery toward the lungs for re-oxygenation. It is a low-pressure pump designed to move blood through the pulmonary circulation. Because its primary function is to deal with blood that has already circulated through the body and lost its oxygen content, it is not the chamber that receives the oxygenated blood returning from the lungs.