Think back to the last time you went to the doctor. It’s becoming more and more likely that you didn’t actually see a doctor. Nurse practitioners now have full practice authority in 22 states around the country, meaning they are able to practice without a doctor’s supervision — including in prescribing medicine.

That’s sparked a debate among some about the increasingly prominent role of nurse practitioners in medicine. Just earlier this spring in Arizona, a pediatrician Green Valley says he was fired after he wrote an op-ed arguing that nurse practitioners shouldn’t be replacements for medical doctors.

So, what is supposed to be the difference between nurse practitioners and doctors? What’s led to this growth in nurse practitioners?

Joyce Knestrick is the president of the American Association of Nurse Practitioners. She says they’ve been practicing for over 50 years, and the growth is a result of the need they’re meeting.

For more on the growing field of nurse practitioners and how they’re different than doctors, The Show sat down with someone who’s been in the field since nearly the beginning. Denise Link has been a nurse practitioner since 1978. Now, she’s a women’s health nurse practitioner and clinical professor in the College of Nursing and Health Innovation at Arizona State University.