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STUDENT D

The heart and circulatory system provide a critical function for humans by delivering oxygen and nutrients the body needs and removing waste products cleansed
The heart is a muscle comprised of four chambers that are divided by a thick wall of muscle called the septum
The right atrium fills with blood from the body and transfers it to the right ventricle through the tricuspid valve
As the heart beats, the blood from the right ventricle is pumped through the pulmonary valve, into the pulmonary veins and down to the lungs
Simultaneously, the left atrium has filled with oxygen rich blood traveling back through the arteries from the lungs
After the chamber fills, blood is sent into the left ventricle through the mitral valve
Blood is then pumped through the aortic valve and into the arteries
The arteries transport the blood and the vital oxygen it carries throughout the body
As the heart beats and empties both the left ventricles and right ventricles, the left atrium and right atrium are again filling with blood
The blood is transferred into the ventricles and sent throughout the body with the next muscle contraction
The heart muscle fills with blood and pumps it out to the body approximately 70 times per minute.