after MS1 - review over summer?

One of my senior faculty members (and best advisor) has strongly suggested that I put in some time reviewing over the summer between MS1 and MS2 (1-2 hrs/day, 5 days/week for most weeks). I’d like some suggestions for what to focus on.
I will almost certainly pass everything this year, but it’s been a lot of work, and the physiology final reminded me of how poorly I understand some of the basic concepts. I am still struggling with concepts like alpha and beta adrenergic responses, protein kinases, cAMP, actions of insulin and glucagon, basic processes of DNA transcription/translation etc… Although I’m a strong conceptual learner, I had to resort to short-term memorization to pass, and now I don’t remember much after the exams. I also feel like I am just beginning to get the bigger picture, and I wonder if review would help solidify everything.
The point behind her recommendation was that I have a relatively weak bio background, and that summer review will help build understanding and confidence for second year. She also says that in her experience, students who have been out of school for a long time often need to put in some extra study time to keep up.
I plan to take vacation; I don’t want to burn out; the second-year students here say not to bother studying. But so far, this faculty member’s advice to me has been wonderful and reliable, so I’m inclined to take it.
Any suggestions for concepts that would be very helpful as a foundation for e.g. pathophys and pharm? Any other ideas?

I won’t speak to whether or not your advisor’s advice is good for you or not, because obviously she has more experience and knowledge than I do working with students, but I will say I found that I too had trouble with some of the concepts you’re mentioning and went to short term memorization during my first year-- but the important stuff gets repeated over, and over, and over again. I particularly noted that you had problems with alpha and beta receptors, and I chuckled, because I just COULDN’T get that-- until one day it clicked. And I still occasionally have to really think about it, or look it up. It WILL come to you with time and repetition that you will get in classes. If you DO decide to study over the summer, I would highly recommend “Pharmacology” by George Brenner. It’s an okay Pharm text, but I really like the diagrams and explanation of the physiology of different systems, and how the drugs work. It is how I finally got the receptors down, not to mention lipids, and some of the CAMP stuff. There is a good review of pertinent physiology in each section. It’s paperback and pretty easy to read.
However I must say, I can’t imagine studying over the summer after first year. It was the last significant break for me, since we went from first, to board study, and then, in my case since I studied for boards for six weeks, only a week vacation before second year. This year I will get a week between third and fourth year (yippee- five more weeks until fourth year). I NEEDED that break. Academically could the studying have helped-- probably. Did the break help? ABSOLUTELY. The mental rest is important, too.
Whatever you decide about studying this summer I just wanted to let you know that the feeling that you haven’t learned everything you need to is VERY common, and you have probably retained more of the “short-term memorization” stuff than you realize. It will come back with repetition.
Good luck, and have a great summer.