how important are reference letters?

I'm kind of worried about my references. I'm applying to Mizzou. I graduated almost 10 years ago with my BSN and the instructors who would have remembered me are no longer at the school i graduated from. I was able to track down one, and she is my only academic reference. The other is actually a friend who has her MSN and was my supervisor. But my third has an MS but its in social work I think. She was the HR manager where I used to work. She is the one I'm worried about that they will not accept a reference from because she is not a nurse. The reference guidelines are a little vague, but I think they are looking for MSN/DNP's whom you have worked for or were an instructor. The only other MSNs/DNPs are friends. What do you think???