What does the atrium do in human body?

The atrium is the upper chamber of the heart. There are two atria, one on the right side and one on the left side. The atria receive blood from the body and lungs and pump it to the ventricles.

The right atrium receives blood from the body through two large veins called the superior vena cava and the inferior vena cava. The superior vena cava brings blood from the head and arms, while the inferior vena cava brings blood from the body below the heart.

The left atrium receives blood from the lungs through four pulmonary veins. The pulmonary veins bring oxygenated blood from the lungs to the heart.

The atria contract at the same time, which helps to fill the ventricles with blood. The ventricles then contract, which pumps the blood out of the heart and to the body.

The atria also play a role in regulating the heart rate. The atria contain special cells called pacemaker cells, which generate the electrical impulses that cause the heart to contract.