What valves must blood pass through to exit the heart?

To exit the heart, blood must pass through the pulmonic valve and the aortic valve.

The blood first leaves the right ventricle through the pulmonic valve, which directs it into the pulmonary artery leading to the lungs. Here, carbon dioxide is exchanged for oxygen. Once the oxygenated blood returns to the heart, it enters the left atrium and then flows into the left ventricle, where it is pumped out through the aortic valve into the aorta. The aortic valve serves to prevent backflow into the left ventricle when the heart relaxes.

Understanding the roles of these valves is crucial for comprehension of the heart's function in circulation. The pulmonic and aortic valves are part of the semilunar valves, which facilitate blood flow out of the heart, while the atrioventricular valves (such as the tricuspid and mitral valves) regulate blood flow between the atria and ventricles, playing a different role in the cardiac cycle.