Which of the following describes how the circulatory and excretory systems work together to maintain homeostasis? by delivering oxygen to cells by having cells that fight infections by delivering nutrients from food to cells by carrying waste to the kidneys

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