The hollow center of your heart is divided into four sections, called chambers. Each chamber is like a separate room, with doors that let blood in and out.
Where Blood Flows In The Atria
The two upper chambers in your heart are called the atria (Figure 1). The atria are the receiving chambers of your heart. When blood flows into your heart from the body or lungs, it always flows into either the right or left atriumnever anywhere else. (One upper chamber is called an atrium. Both upper chambers together are called the atria.)
Where Blood Is Pumped Out The Ventricles
The two lower chambers in your heart are called ventricles (Figure 1). The ventricles are the pumping chambers of your heart. When blood leaves your heart, it is always pumped out from the ventriclesnever from anywhere else. The ventricles are very strong because they have to pump hard enough to push blood through your lungs and entire body.
Your Heart's Right and Left Sides
Sometimes the right and left sides of your heart are called your right heart and left heart. The right atrium and right ventricle are, of course, on the right side of your heart (the same side as your right arm), and the left atrium and left ventricle are on the left side of your heart. However, when you look at a picture of the heart, the right heart is on your left (like in Figure 1).
A wall, called the septum, separates the left and right sides of your heart. Blood that hasn't yet been to the lungs (blood with no oxygen) stays on the right side of the septum. Blood returning from the lungs (blood with oxygen) stays on the left side of the septum.
Next: Heart Valves
Q. What are the atria in your heart?
The two upper chambers in your heart
The two lower chambers in your heart
One of the upper chambers in your heart
Q. The ventricles are the pumping chambers of the heart.