How do heart valves function in the cardiovascular system?

Heart valves play a critical role in ensuring unidirectional blood flow through the heart and into major blood vessels. Their main function is to open and close in response to pressure changes within the heart chambers. When the heart muscle contracts, it generates pressure that causes the valves to open, allowing blood to flow from one chamber to another or into the arteries. Once the heart muscle relaxes, the pressure within the chambers decreases, causing the valves to close and prevent backflow of blood. This mechanism is essential for maintaining efficient circulation and proper functioning of the cardiovascular system.

The heart's electrical system does coordinate the timing of heartbeats and muscular contractions, but it is the pressure changes that directly dictate the movement of the valves. The other options do not accurately reflect the valves' primary function; they do not remain permanently open, as that would disrupt the flow of blood, and they do not filter blood impurities, which is a function of the kidneys and other organs.