Frankly, the most typical trajectories that I see (limited now to people who interview) is almost flat (3.90 or better every year), or the Nike swoosh with a dip sophomore year (almost always attributable to Organic Chemistry) followed by an over-correction junior year (i.e. higher than freshman year) and still higher senior year (if applicable).
Some people will have an upward trajectory because they had a hard time adjusting to college life and/or the study skills needed in college or they were not pre-med, didn't fret about grades and thought that 3.0 was more than fine given that 2.0 or higher is keeps you off of academic probation. When someone in that boat realizes that they'd like to apply to medical school (or graduate school) they wake up and get serious about earning higher grades. There are also places where the 100 and 200 level courses are "weed out" and once the weaker students have been culled, the higher level classes are aught in a way that is "easier" for those who have mastered the basics.