ANATOMY

Detailed explanation-1: -Oxygen-rich blood flows from the lungs back into the left atrium (LA), or the left upper chamber of the heart, through four pulmonary veins. Oxygen-rich blood then flows through the mitral valve (MV) into the left ventricle (LV), or the left lower chamber.

Detailed explanation-2: -Normally, each pulmonary vein connects directly with your left atrium. In that case, there are four ostia (openings) in your left atrium, one for each of your pulmonary veins. Oxygen-rich blood travels through these openings and into your left atrium.

Detailed explanation-3: -Mitral valve: This valve has two leaflets. They allow blood to flow from the lungs into the left atrium. And they prevent backward flow from the left ventricle to the left atrium.

Detailed explanation-4: -Left atrium: one of the four chambers of the heart. The left atrium receives blood full of oxygen from the lungs and then empties the blood into the left ventricle.