The heart valves control the direction of flow of blood through the heart. After passing through the tissues of the body, the blood collects into the veins and returns to the right atrium. Blood then passes through the tricuspid valve into the right ventricle. The right ventricle pumps the blood through the pulmonary valve into the arteries of the lungs where the blood picks up oxygen and gives up carbon dioxide. The oxygenated blood returns to the left atrium after which it passes through the mitral valve to the left ventricle and the cycle repeats Like all tissues in the body, the, heart requires oxygen filled blood in order to function.
Blood nourishes the heart through the right and left coronary arteries.
The left main coronary artery gives off two major branches, the circumflex and obtuse marginal arteries, before it continues as left anterior descending artery. Figure 1a - The heart viewed from in front showing the position of the right and left atria and ventricles. The yellow arrows show the direction of blood flow through the valves. The yellow arrows show the direction of blood flow through the valves. The coronary arteries become narrowed with the deposition of fatty or calcified material on the inside of the artery.