Monday
Feb152010

Heart Overview

The heart is brilliant machine, capable of pumping blood to the entire body without interruption for a lifetime.  To give a sense of the workload that is completed, one can estimate around 3 billion heartbeats in the lifetime of a 60 year old heart (100 beats/minute x 60 minutes/hour x 24 hours/day x 365 days/year x 60 years = 3,153,600,000 heartbeats!!!)

The elegant design of the heart allows for this tremendous workload.  There are four chambers and four heart valves in the human heart, which can be broken up into the right heart and the left heart.  The right heart takes blood from the body and pumps it through the lungs to re-oxygenate red blood cells.  The left heart then takes this re-oxygenated blood and pumps it to the rest of the body.

 Human Heart DiagramHuman Heart Diagram

The Right Heart

The right side of the heart is composed of the right atria and the right ventricle.  After blood has delivered oxygen to the body for energy, the de-oxygenated blood is returned to the right atria by the body's veins.  This blood flows into the right atria, which acts as a holding chamber.

As soon as the heart is resting, this blood flows past the tricuspid valve and into the right ventricle.  Once the right ventricle is full, the heart will squeeze blood from the right ventricle into the lungs, where it can be re-oxygenated.  As the blood flows into the lung arteries, it passes by the pulmonic valve, which ensures that the blood will stay in the lungs and not flow back into the right ventricle.

The Left Heart

After blood has been re-oxygenated in the lungs, it flows into the left atrium.  Similar to the right atrium, the left atrium holds blood until the heart relaxes and can flow into the left ventricle.  Blood from the left atrium passes through the mitral valve on its way to the left ventricle.  Once the left ventricle has filled, the heart contracts and pumps blood through the aortic valve to the rest of the body.

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