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How the Heart Works: Part 1

Updated on December 1, 2013


I'm going to attempt to explain the heart in such a way that a layman can gain a basic understanding of what it does and how it pumps. Hopefully working as a cardiac ICU nurse for a few years has helped me become proficient at this job. This article will cover the basic anatomy of the heart, and nothing more.

See page for author [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons
See page for author [GFDL ( or CC-BY-SA-3.0 (], via Wikimedia Commons | Source

The Chambers

Let's start with this: your heart is a muscle. Its pumping action is what supplies your body with oxygenated blood (oxygenated blood just means that the blood is carrying oxygen), and that is its only purpose. It keeps everything flowing.

Your heart is comprised of 4 chambers. These are the atria (top part of the heart) and the ventricles (bottom, stronger part of the heart). The left side of your heart is stronger than the right, and this is for a very simple reason. When a person works a certain muscle, such as bodybuilders will do with weights, the muscle grows larger to accommodate increased stress. The left side of your heart pushes against more pressure than the right, so it's slightly larger.

The atrium's job is a simple one: provide that little extra kick of blood to the ventricles. Blood will flow passively into the ventricles. The beating of the atria just adds that little extra. For this reason, the top part of your heart (atria) beats first, followed by the bottom (ventricles). And because your atria don't have to push against much pressure, they're weaker than the ventricles.

Valves and Arteries

There are also valves at each juncture of the heart. There's one from the atria to the ventricles, and from the ventricles to the arteries connected to them. These valves ensure that when blood is pushed forward by the beating of the heart, it doesn't just flow backwards and waste that energy. For example: blood is allowed to flow into the ventricles from the atria. The valve between these chambers stays open until the pressure in the ventricles is higher than in the atria. When that happens, and blood starts to flow back to the atria, it pushes the valves shut.

The final piece of the heart anatomy puzzle are the veins and arteries connected to it. Blood returns to the heart via the superior (top) and inferior (bottom) vena cava. Vena cava is just the official name of the veins that blood returns through. Blood then travels from the right ventricle to the lungs through the pulmonary artery. After the blood has been oxygenated it returns to the left atria through the pulmonary vein, then leaves the left ventricle through the aorta (another artery).

Sounds complicated, I know. But just remember, the entire purpose of the heart is to push oxygenated blood through your body. So un-oxygenated blood gets to the right side of the heart, goes to the lungs to become oxygenated, then leaves the heart destined for the rest of your body with all its oxygen filled goodness.

I hope this has helped. For more information on the heart, and the different complications that might arise, just check out some of my other hubs.


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