From what I've read on the forums, Kaplan's review of human physiology is lacking (ever have that feeling while reviewing that there's a lot missing). For instance, the infamous Sea Urchin question can probably be answered based on a knowledge of human development. But, the level of detail required for the answer (zona pellucida, vitelline space, cortical rxn for preventing polyspermy) is not even mentioned in Kaplan's. In general, it's probably not a bad idea to go a little more in depth on most of the subjects. I've heard of people using Schaum's for extra review and examkrackers bio for human physiology, genetics, microbio (all mcat topics, basically). Examkrackers very briefly mentions the cortical rxn on page 115 of their bio review.
Of course, I haven't taken the test yet...so I wouldn't really know...but, nobody else is answering you...