Function of the heart.

The funtion of the heart is to supply the body with oxygenated blood. In humans this is done by use of a double circulatory system. This means that the blood enters the heart twice before it is pumped to the rest of the body. De-oxygenated first enters the right atrium via the vena cava and drains into the right ventricle. Once the right ventricle is almost full, the right atrium forces the last bit of blood in and the tricuspid valve closes. The right ventricle then squeezes its contents up through the pulmonary arteries where the blood is taken to the lungs to be oxygenated.Once oxygenated, the blood makes its way back to the heart via the pulmonary vein and into the left atrium. Again the blood drains into the left ventricle and when it is almost full, the left atrium forces the last bit of blood in at which point the mitral valve closes. The oxygenated blood is then pumped at high pressure to the rest of the body via the aorta.