The aortic valve is located at the root of the aorta at its junction with the left ventricle. It is a high pressure, cusped, semilunar valve that must withstand tremendous pressures during left ventricular ejection. Again, if the valve becomes incompetent, blood can flow back into the left ventricle during systole (ejection). This can lead to ventricular overload and pulmonary vascular congestion as well as forward perfusion issues. Both ostia of the coronary arteries are located at the aortic valve near the sinuses of Valsalva. If ventricular ejection is decreased either through poor contractility or incompetent aortic valve, coronary artery perfusion can be affected. Compare the left and right sides of the dissected heart. What differences do you see? When the dissected human heart is laid flat, both atria and ventricles can be seen. In this view, it is very obvious how much more muscular the left ventricle and even the left atrium is, when compared to the right side of the heat. The interventricular septum bows slightly into the right ventricle. The left ventricular chamber is larger in size and the left atrium is also larger In the right and left ventricles you can see the papillary muscles and chordae tendinea that attach the tricuspid and mitral valves to the interventricular wall. In the right ventricle there are trabeculae, light finger like projections that are not readily noted in the left ventricle. Compare and contrast the functions of the atria and the ventricles. Both atria are receiving chambers, with the left larger and more muscular than the right. The right atrium receives systemic, deoxygenated blood from the superior and the inferior vena cava and deoxygenated cardiac blood from the coronary sinus. The left atrium receives oxygenated blood from the pulmonary circuit via the multiple pulmonary veins in the left lateral wall. The right atrium is also the home of the heart’s electrical system. The sino-atrial node (SA node) is located in the roof of the right atrium and is the primary pacemaker of the heart maintaining an inherent rhythm and rate of between 60 and 100 beats per minute. In the floor of the right atrium, near the junction of the atrium and the interventricular muscular septum is the atrioventricular node. The AV node or junction is a backup pacemaker of the heart, designed to come in as an escape mechanism if the SA node fails as can happen in cardiac disease or sometimes drug ind>