I assume from your post you are going into RN school. Where i work the RN's duties are mostly paper work, emergency care that are sent to the medical unit and care of the inmates in the infirmary. The LPNs work the actually housing units of the inmates. Each shift is a bit different for the RN who acts as a charge nurse. Days and Evenings take off doctors orders placing them on the MARs and on the pharmacy order form, Days tracks the treatments done by the LPNs evenings track the Sick call done by the LPNs. Nights triage the sick call request to go either on the nurses sick list or the doctor's, answer the complaint forms submitted by the inmates and helps with the lab (labs are usually done by an LPN, but the RN helps when she's overloaded), and does chart review on the orders, MARs and pharmacy order forms.
It's an exciting career, no two days are ever the same! I've been told by a nurse that use to work in the ER that correctional nursing was similar in that you never knew what to expect from one day to the next. We've had staff injuried by the inmates and have to care for them as well.
You mentioned documentation stating it was a sad atmosphere. From the inmate point of view, I'm sure it is. The key for me is not to get emotionally involved. I keep in my mind that these are men that have killed and raped. They're there for life, either to die from natural causes, have a death sentence or are killed in prison. Either way they are not going anywhere soon. I'm professional in the care I administer, yet stern and consistent in the way i administer care. I do know favors for any inmate, I don't give them an inch for they will take a mile or more if given half the chance, and then you're standing in the unemployment line!
All in all I love what I do and wouldn't go back to caring for normal "free" people on the street.