There are lots of ways to “go to the doctor” now. Since we all end up needing healthcare at some point, it would be useful to have a working knowledge of what sort of healthcare providers are lurking about our assorted hospitals and clinics, wouldn’t it?

Physicians, as a rule, fall into two categories in America. They (we) are either allopaths (known as M.D., or medical doctor) or osteopaths (known as D.O., or doctor of osteopathy). The difference lies in the history of modern medical schools. So I won’t have to bore you with obscure discussions of medical philosophy, I’ll just say this: An M.D. and a D.O. are functionally the same. D.O. physicians tend toward primary care, but can also be found in the same specialties as M.D. physicians. However, our D.O. brothers are trained in musculoskeletal manipulation along similar lines to chiropractors. If you are in the clinic, or the hospital, it really doesn’t matter a bit which of the two your physician happens to be.

In order to practice as a physician, one must complete an undergraduate degree with particular prerequisites, then attend a four-year medical school, followed by an internship and residency training in a specialty. These programs are anywhere from three to seven or more years, depending on the specialty one chooses. (If your surgeon looks tired, it’s just that he’s been awake for about six years in training.)

But times are a-changing, aren’t they? You may also be confronted with a nurse practitioner or physician assistant, especially since we’re experiencing a serious shortage of physicians in America. Nurse practitioners are persons who have four-year nursing degrees, followed by either a master’s degree or, increasingly, a Ph.D. or D.N.P. (doctor of nursing practice) that focuses on diagnosis and treatment of patients beyond standard nursing care. While they do not practice as physicians, they are more highly educated caregivers and will continue to increase the quality of care patients can expect. Typically, they work in concert with and under the supervision of physicians.

One more general species remains, and that’s the physician assistant, or P.A. The P.A., like a nurse practitioner, is considered a “mid-level” provider. That is, they are trained in a shorter, more focused (and fortunately for them, less expensive) manner than a physician. P.A.s have an undergraduate degree, then have two years of intensive schooling and clinical rotations with physicians. Their training, which usually results in a master’s degree, looks remarkably like medical school — if you took medical school and threw it in the dryer on high and made it shrink.

Like nurse practitioners, they can change from primary care to specialty care as their interests and job markets allow. Both groups provide excellent care. And it’s not unusual for patients to enjoy their time with mid-level providers a little more than with grumpy, harried and hurried doctors like myself; they sometimes have more time to spend with patients than their supervising physicians. (We’re usually too busy filling out paperwork or typing at a keyboard.)

So the next time you’re sick, hurt or just getting a checkup, you’ll know the difference between the various creatures that run around in lab coats with stethoscopes around their necks. But remember, whether D.O., M.D., P.A. or N.P., they’re well-trained and caring, and will do their best to keep you healthy.

— Edwin Leap is an emergency physician and writer who lives with his wife and four children in Walhalla. Read more at EdwinLeap.com.