How the blood flows
lungsoxygen goes to the lungs
Step 1Blood returns to your heart from your body and lungs.
Oxygen-poor blood from your body flows into your right atrium.
At the same time, oxygen-rich blood from your lungs flows into your left atrium.
Step 2Blood flows from the upper to the lower chambers.
Blood flows from your right atrium into your right ventricle.
At the same time, blood flows from your left atrium into your left ventricle.
Step 3STEP 3. Blood is pumped back out to your lungs and body.
Your right ventricle pumps blood out of your heart to your lungs, where the blood's oxygen supply is replenished.
At the same time, your left ventricle pumps blood — once again full of oxygen — out of your heart to your body.
step 4The oxygen-poor blood returns to the heart and then to the lungs to get refilled. The cycle begins again.