I've recently done the cardiac cycle in biology and though I found it very interesting, I've found it quite difficult. Usually I do really well in biology but this really threw me off. It's not the actual cardiac cycle itself, it's more do to with graphs, calculating bpm, pressure changes, valves in the veins etc rather than the actual cycle because that's simple, if that even made sense at all? Anyway, it would be great if somebody could explain all of the graphs and calculations and pressure changes i.e. the more challenging sub-topics of the topic that would be great. Thanks!