The Heart

The Heart is one of the body's major organs. The function is to pump blood around the body for use by it. The human pulmonary system is a double circulation system, this means it firstly pumps blood to the lungs where it is re-oxygenated it is then pushed  back into the heart where it is pumped back round the rest of the body at a much higher pressure.

A diagram of the heart showing the different chambers, veins and arteries
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The human heart is split into two different halves each half is fairly similar having two chambers each. the right side pumps the blood round to the lungs as a result it is much smaller as it does not need as much muscle as the pressure does not need to be as high. The vein leading into the right side of the heart(not annotated on the diagram) is the vena cava, this leads into the right atrium. In the first cycle it gently pushes the blood into the ventricle. The ventricle produces the pressure required to push the blood from the heart, this squeezes much harder than the ventricle to produce a much higher pressure.The triscuspid valve prevents blood being pushed back into the atrium, similarly the pulmonary valve prevents blood from being sucked into the ventricle from the pulmonary vein. The pulmonary artery brings blood to the lungs away from the heart, and the pulmonary vein brings blood back into the left side of the heart. The left side of the heart is pretty much the same however its the bicuspid (mitral) valve that separates the two chambers and its the aortic valve that separates the aorta and the left ventricle.