Heart Blood Flow
The heart acts as the central pump for the circulatory system. It can be thought of as having two halves. The right half includes the right atrium and right ventricle that are separated by the tricuspid valve. The left half includes the left atrium and left ventricle that are separated by the mitral valve.
De-oxygenated blood enters the right half of the heart from the superior and inferior vena cava. These are major veins collecting oxygen-poor blood from the upper and lower parts of the body, respectively. From the right atrium, the blood flows through the tricuspid valve to the right ventricle. The tricuspid valve prevents the blood from flowing backward between heart beats. The right ventricle pumps the blood out the pulmonary valve into the pulmonary artery that goes to the lungs.
In the lungs, the blood picks up oxygen and releases carbon dioxide. This oxygenated blood flows back through the pulmonary vein to the left atrium. The blood then travels through the mitral valve to the left ventricle, and is then pumped through the aortic valve to the aorta. The aorta branches into the many arteries, and then capillaries, delivering oxygenated blood to the body's organs, tissues and cells. Once the capillaries deliver the oxygen to the cells, the now deoxygenated blood travels through venules into veins, and then to the superior and inferior vena cava to start all over again.
Both left and right sides of the heart pump blood at the same time. The blood is pumped out of the heart each time the heart muscle contracts or beats. This is called the systole. This pumping takes place in two stages. First the right and left atria contract pumping blood into the right and left ventricles, respectively. Then the ventricles contract pumping blood out of the heart. The heart muscle then relaxes, called the diastole, and the heart fills with blood again before the next heartbeat.
Coronary arteries are the ones that we try to keep clear by eating a healthy diet. If Coronary arteries are blocked a heart attack results.
The heart, just like any other organ, requires blood to supply it with oxygen and other nutrients so that it can do its work. The heart does not extract oxygen and other nutrients from the blood flowing inside it. The heart gets its blood from coronary arteries that eventually carry blood within the heart muscle.