Once blood deoxygenated blood enters the right atrium through the superior and inferior vena cavas and the coronary sinus the atrium contracts and the blood passes through the tricuspid valve into the right ventricle. The ventricle contracts and the blood is pumped through the semilunar valve and away from the heart through the pulmonary artery to the lungs. The blood is reoxygeneated by releasing co2 and picking up o2 in the lungs. The blood then travels back to the heart, this time oxygenated blood enters the left atrium, it contracts and blood passes through the bicuspid valves into the left ventricle .The left ventricle is more muscular than the right because the oxygenated blood has to be pumped around the whole body. When the ventricle
