The chamber of heart that receives oxygenated blood from lungs is :

Correct Answer: A. Left atrium

The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle. In the lungs, the blood oxygenates as it passes through the capillaries where it is close enough to the oxygen in the alveoli of the lungs. This oxygenated blood is collected by the four pulmonary veins, two from each lung. All four of these veins open into the left atrium that acts as a collection chamber for oxygenated blood. Just like the right atrium, the left atrium passes the blood onto its ventricle both by passive flow and active pumping.

• Option B: The right atrium receives blood from the veins and pumps it to the right ventricle. The right atrium receives deoxygenated blood from the entire body except for the lungs (the systemic circulation) via the superior and inferior vena cavae. Also, deoxygenated blood from the heart muscle itself drains into the right atrium via the coronary sinus. The right atrium, therefore, acts as a reservoir to collect deoxygenated blood.
• Option C: The left ventricle (the strongest chamber) pumps oxygen-rich blood to the rest of the body, its vigorous contractions create the blood pressure. Oxygenated blood thus fills the left ventricle, passing through the mitral valve. The left ventricle, which is the main pumping chamber of the left heart, then pumps, sending freshly oxygenated blood to the systemic circulation through the aortic valve
• Option D: The right ventricle receives blood from the right atrium and pumps it to the lungs, where it is loaded with oxygen. The right ventricle pumps blood through the right ventricular outflow tract, across the pulmonic valve, and into the pulmonary artery that distributes it to the lungs for oxygenation.