Answer:the heart has 4 chambers 2 upper called atria and2lower ventricles. The atria reserve blood returning to the heart(poor-blood). The thick- muscled ventricles pump blood out of the heat. The right ventricle pumps blood to the lungs through the pulmonary trunk; at the base of the pulmonary trunk is the pu semilunar valv, which prevent backflow of blood into the right ventricl. The left ventricle pumps blood to the systemic circui through the aorta; at the base of the aorta is the aortic semilunar valve, which prevents backflow to the left ventricle. The superior and the inferior vena cavae brings blood back from the systemic circuit to the right atrium.
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