The Clean Water Act of 1972 is one of the most important pieces of legislation in U. S. history. Separate the issues based on whether the Clean Water Act of 1972 was effective in dealing with them or not.

1. beginning with all chambers of the heart in the "relaxed" phase, describe the cardiac cycle in mammals, with systole and diastole of the atria and ventricles. for each time point in the cycle you select, state the following: • whether the atria and ventricles are contracting or relaxing • whether the av valves and semilunar valves are closed or open • whether the pressure in the atria and ventricles is high or low