As a current pre med student, I can tell you that medical schools don't care what your major is. You can major in sports history, art, or any other non science major and still get in. However, you do have to have a high total GPA and a high math and science GPA.
However, almost every med school requires the following 8 courses:
General Biology 1 with lab
General Biology 2 with lab
General Chemistry 1 with lab
General Chemistry 2 with lab
Organic Chemistry 1 with lab
Organic Chemistry 2 with lab
General Physics 1 with lab
General Physics 2 with lab
None of these courses have to contain any calculus.
The following is a list of some other courses that are either required or recommended by certain medical schools:
Anatomy
Physiology
Biochemistry
Cell biology
Molecular Biology
Genetics
Calculus
Assorted Humanities
In addition, It is very advisable to engage various extracurricular activities, like biomedical research(most premeds do that in the summer), shadowing a doctor, volunteering in a hospital, getting an EMT license (and possibly working as one, in either an ambulance or an ER).
There is a medical admissions test called an MCAT (Medical College Admissions Test). The highest score on it is a 45T. It consists of three sections and an essay (which they don't care about, except if it is between you and another person for the last seat in an incoming class, they will look at the essay grade) which is marked from j (lowest) to t (highest). There are 15 point for each section. There is a Biology and Organic Chemistry Section, a General Chemistry and Physics section, an a Verbal Reasoning (think very hard reading comprehension) section. Calculators are not allowed, since the math on the test is easy. All answers are multiple choice. It is very hard.
I will now list the minimum requirments that a white or asian male needs to have, in order to be a competitive medical school applicant. if you are not a white or asian male, the requirments are lower
3.5 total GPA (the higher the better)
3.5 math and science GPA (the higher the better)
at least a 10 on each section of the MCAT ,for a total score of 30 (the higher the better) (from what I understand, they would prefer a 10 10 10 to a 15 15 9, since the like balance

)
lots of extracurricular stuff
good letters of recommendation
a good essay and good interview skills (the average med school receives 4000 applications, interviews 400, and accepts 100. They read a essay that you write to them with your application in which you try to give them a reason for admitting you)
good luck