This may seem goofy but...
spend some time playing with a garden hoses... turn the water up high and low... put your finger over the end... get some pvc fittings and neck it down (keeping the faucet the same, etc. Play with straws and water and milk and oil (different viscosities)... Play with water balloons... try squeezing them different ways to see what happens... fill them different amounts and see what happens.
Ideally, get a cheap pressure meter (mcmaster-carr has anything you'd ever want) and try to correleate pressure to what you observe.
Try to develop a sense of hydrodynamics and you will find hemodynamics much easier to understand.
then, think about the basics of what the heart is trying to do: get blood to the lungs to dump waste and pick up oxygen and then get it to the brain and other tissues to deliver nutrients, oxygen, and signals and pick up waste to be processed by the liver and excreted through the kidneys and lungs.
The basics are very, very simple but even the details aren't that bad when you break them down and think of analogues with which you're familiar.
(Damn do I want to be a nursing instructor.)