Pick a college that suits your personality and a major that interests you. You will need to get good grades in college in order to apply for medical school. At the medical school I attended, the average GPA is reported to be 3.85, so even one or two B's can hurt your chances of acceptance.
Aside from this, any major is acceptable as long as you complete the prerequisite courses.
Typical medical school prerequisites include:
Biology: Lecture – 4 semesters; Lab – 1 semester
General Chemistry: Lecture – 2 semesters; Lab – 1 semester
Organic Chemistry: Lecture – 2 semesters; Lab – 1 semester
Biochemistry: Lecture – 1 semester
General Physics: Lecture – 2 semesters; Lab – 1 semester
Math: Statistics – 1 semester
English: Rhetoric (Composition) and Literature – 2 semesters
During college study for and complete the MCAT. Apply to medical schools during your last year of college.
Medical school takes 4 years to complete.
After medical school physicians complete a residency for anesthesiology.
1) Get accepted to and complete a 4 year degree at any college. This is where you have the freedom to complete a degree in any field that you enjoy. A lot of students have science degrees (biology, physics, chemistry, psychology, etc.) but they aren't required and other degrees can help you stand out from the pack. The only required undergraduate pre-requisites before applying to medical school are taking the required pre-requisite classes and scoring as well as you can on the MCAT. Research, volunteer work and work/shadowing experience are also highly recommended to show off your experience and unique perspective on medicine. This may seem like a lot, however, every college should have a pre-med advisor who will help you and make sure you have everything you need to apply. These advisors are available to you no matter what degree you decide to pursue so don't feel pressured to do something you don't enjoy.
2) Take the MCAT and get accepted to any accredited medical school.
3) A MD or DO school both give you the same options to pursue a residency in anesthesia or any other specialty that you gain an interest in throughout the process. Medical school is also 4 years long and then you are free to apply to an anesthesia residency.
4) Anesthesia residency is 3 years but other residencies can be as long as 7 years, most are around 3-4. After residency you take your licensing exams and you'll be fully licensed and certified by the medical boards to practice as an anesthesiologist!
I know this seems like an extremely long and confusing process but you'll meet so many advisors, mentors and advocates along the way who are always willing to help. Good luck!