Question: How does the heart work?

Sara Falcone answered on 19 Nov 2015:

It works just like a pump that is activated by an electric impulse .
The blood arrives in the first chamber ( the atrium ) and stays there until the atrium has an electric impulse telling it to contract . When it does, the blood goes down in the second chamber , the ventricle . The impuls travels into the heart muscle to the ventricle so it can contract too and send the blood out side, to the body or to the lungs. Because we have two atria and two ventricles, the blood can be send to the body and to the lungs ( where it gets the oxigen and gets rid of the CO2 ) at the same time.
Also, to prevent the blood flowing in the wrong direction , there are valves between the atrium and vetricle that only open when the atrium has to pass the blood to the ventricle . The sound of the heart beat is actually the sound of those valves closing.