One great way to approach some difficult concepts in physiology is to make it applicable. Go back to the basic concepts and then discuss or think about what diseases can occur from dysfunction at that particular area. By doing this you almost work backwards in a sense so you'll see the end result and then discover why it's happening. You can also do this by looking at nutritional aspects and medications that work on different parts of the body. A great example I've done with a student is discussing the Hypothalamus-Pituitary-thyroid axis. We talked about the axis itself and how it works. We then talked about what happens if hormones break down along the way or formation is halted and the diseases it will cause like hypothyroidism or hyperthyroidism. After we discussed the disease processes we could go back and review how typical treatments work on the different parts of the axis. This way you make sure you fully understand the proper physiological processes and also how they can go wrong and the effects it may have on the body.