500
The blood arriving at the heart from the body enters the (1) _into the (2) _passing through a valve (3) _to the right ventricle. The blood passes through another valve (4) _ into the right and left (5) _. Blood then travels to the lungs to pick up fresh oxygen and drop off carbon dioxide. It returns to the heart by the (6) _ to the (7) _. Blood leaves here via the (8) _ to once again circulate throughout the body.
What is 1 inferior and superior vena cava, 2-right atrium, 3-tricuspid valve, 4-pulmonic, 5-pulmonary arteries, 6-pulmonary veins, 7-left atrium and ventricules, 8-aorta