Transport in mammals: explain question

A student makes the following statement about the cardiac cycle:

"The atrioventricular valves close when ventricular pressure exceeds atrial pressure, and they open when ventricular pressure falls below atrial pressure. The semilunar valves close when ventricular pressure falls below aortic pressure and open when ventricular pressure exceeds aortic pressure."

Using this information and your knowledge of the cardiac cycle, explain how the sequence of pressure changes and valve movements is coordinated by the sinoatrial node, atrioventricular node, and Purkyne tissue.