The cardiovascular system consists of the heart and blood vessels.The left side of the heart pumps oxygenated blood which is blood that has high oxygen and low carbon dioxide concentration. The right side of the heart pumps deoxygenated blood which is blood that has high carbon dioxide and low oxygen concentration. LORD = Left Oxygenated Right Deoxygenated When the left ventricle contracts, blood flows into the aorta. When the right ventricle contracts, blood flows into the pulmonary artery. The Valves The function of the valves is to prevent backflow of blood. The bicuspid valve is found between the left atrium and the left ventricle. The bicuspid valve prevents blood flowing backwards into the left atrium. The tricuspid valve is found between the right atrium and the right ventricle. The tricuspid valve prevents blood flowing backwards into the right atrium. The two semilunar valves are found at the entrances to the pulmonary artery and the aorta. They prevent blood flowing backwards into the ventricles after they have contracted. The semilunar valve at the base of the aorta is called the aortic valve. Sometimes this valve becomes faulty and requires replacement by surgery.A faulty aortic valve alters the flow of blood through the heart because it would allow the backflow of blood from the aorta to the left ventricle The symptoms of aortic valve diesease may include: Shortness of breath Angina (chest pain) Lightheadedness Dizziness Fainting The patient will have these symptoms because not enough oxygenated blood is being pumped out of the heart because of the backflow into the left ventricle. The valve at the base of the other major atery of the heart is called the pulmonary valve.