Question

what happens to the blood when left atrium relaxes​

Answer 1

Answer:

Blood leaves the lungs and returns to the heart entering the left atrium through two veins called the pulmonary veins. The atrium is relaxed (diastole) as blood enters. As the atrium fills, the pressure inside rises. The mitral valve (between the atrium and ventricle) is closed to stop blood entering the ventricle.