C average student - how badly will this affect me

MS1 at a non-P/F DO med school. I am 4 blocks into the semester and am doubtful that I won't finish with any A's, probably 2 B's, and multiple C's in the chunky classes like Anatomy, Pharm, and Physiology. Honestly, right now I am not sure I will pass but I think it will come up in time. That being said, will these C's kill me as they will put me in the bottom quartile? I always overhear classmates talking about how they killed this or that exam, but when I see my own grades I am struggling to get 75's-80's. Am I already limiting my options from semester 1? Am I studying incorrectly?