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The heart is responsible for pumping blood all throughout the body. It is a muscle divided into right and left sides and is separated down the middle by a septum.
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The heart is comprised of four chambers; the right atrium and ventricle and left atrium and ventricle. The heart also has four valves that control the flow of blood into the chambers and arteries of the heart.
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The right side of the heart pumps blood from the heart to the lungs through the pulmonary artery. The left side pumps blood to other parts of the body via the aorta.
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A pumping cycle begins as soon as blood from the rest of the body returns to the heart low in oxygen. It comes through the superior and inferior vena cava to fill the hearts right atrium.
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Once the right atrium is filled with blood, the tricuspid valve opens and it contracts pumping blood into the right ventricle. This is called atrial systole.
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When the right ventricle has been filled with blood the tricuspid valve closes to prevent blood from flowing back into the right atrium.
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The right ventricle contracts once it is full with blood. The pulmonary valve opens and blood is pumped into your pulmonary artery and then on to the lungs. This is called ventricular systole.
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The pulmonary valve then quickly close to prevent any blood from flowing back into the right ventricle.
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Oxygen rich blood returns from the lungs and fills the left atrium of the heart via the pulmonary veins.
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The left atrium then contracts, the mitral valve opens and blood is pumped into the left ventricle. As this is happening a new contraction is occurring in the hearts right atrium.
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When the left ventricle is gull with blood, the mitral valve closes again to prevent blood flowing back into the left atrium.
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The hearts left ventricle contracts and the aortic valve between the left ventricle and aorta opens. This means that oxygen rich blood can be pumped into the aorta and on to the rest of the body.
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The aortic valve close quickly to prevent blood flowing back into the left ventricle. This occurs at the same time a new contraction is happening in the hearts right ventricle.
Then the cycle just begins again and this happens every second, every minute, every day of your life. On average, if a person's heartbeat maintains at 75 beats per minute, their heart would beat 108000 times per day.