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Introduction

How do the heart and lungs interact?

The heart and lungs are very closely connected. Not only do they fit closely together in the chest, but they also work together to make sure that every part of your body gets the oxygen it needs.


In our discussion of how the heart works, we said that blood is pumped from the right side of your heart to your lungs. Just like the air you inhale moves through passageways, the blood that flows through your lungs moves through a set of branching pipes called pulmonary vessels. The biggest pipes are called pulmonary arteries; as the vessels move deeper into the lungs, they divide into smaller and smaller branches, eventually becoming a large network of very thin-walled vessels called capillaries. These vessels are important because they are the site of oxygen transfer from the alveoli, across the alveolar and capillary walls, into the blood. If there is trouble with the pulmonary vessels, you may have difficulty getting oxygen into the blood.


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In our discussion about how the lungs work, we said that you need oxygen as fuel for everything you do. To help you better understand how the heart and lungs interact with each other, let's follow the journey of an oxygen molecule in the air you inhale. Starting from your mouth or nose, the oxygen molecule moves through smaller and smaller airways until it reaches tiny air sacs known as alveoli. There, the oxygen molecule moves across the thin walls of the alveoli and blood vessels into the blood where it is carried inside a red blood cell. As you may remember from our discussion of how the heart works, this blood was pumped from the right side of the heart and is now passing through the lungs on its way to the left side of the heart. After being carried in the blood to the left side of the heart, the red blood carrying the oxygen molecule is then pumped out to the rest of the body.


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