How your heart works
Your heart is a muscular organ about the size of your fist. It supplies blood, containing all the oxygen and nourishment you need, to every part of your body. Most people imagine their heart as a pump but it’s actually two pumps with four separate chambers. The upper two chambers are called the atria. The lower two are your ventricles.
The atria receives the blood returning to the heart and pushes it to the ventricles, the larger chambers of your heart.
Your right atrium receives the blood from your body that’s delivered most of its oxygen to the muscles and organs. It passes it to the right ventricle which pushes it to your lungs where it picks up oxygen. Blood returning from your lungs then arrives in your left atrium, which pushes it down to the left ventricle. Being the larger, stronger ventricle, it pushes oxygen-rich blood out of your heart to circulate through your entire body.
Blood circulates in an endless figure-eight loop.
