obviously, and i know you have done this in the past, the best way to learn a formula is to associate what it means with the formula itself. with some of the formulas that you are having a hard time understanding, force yourself to describe why it makes sense or transform the words and variables into a picture. by doing that, you're forcing yourself to understand the concept. this may sound stupid, but you can make a game out of understanding it. rote memorization is unnatural and will be more difficult to apply to problems or clinical situations in the long run.
For example, in calculating clearance (which seems like a pervasive concept in renal phys), the formula is C=(UxV)/Px.. memorizing it wont do you all too much good if you don't really understand it.. the concept is very simple.
The description you will find in the book may not make complete sense to you. In which case, reword what they are saying in your own words without losing the meaning. Clearance is defined as "The volume of plasma from which the substance is cleared completely per unit time." Relating it to C=(UxV)/Px and asking yourself why it is important to know this may help put it all together.
like the previous poster was alluding to, association and understanding is so much better than memorization especially in a conceptual course like physio. in physiology, look at memorizing like telling lies. you want to do it as little as possible. because when you do it once, you'll have to do it again and again. but if you understand the concepts they merge together because of the inter-relatedness of the topics within the subject and ultimately don't feel as heavy in your mind - making it much less likely that you will forget, get confused, or be easily tricked.. not to mention, a solid understanding of physio concepts will make pathology and pharmacology more understandable.
good luck.
