Hello Beth, welcome to the site. Here you can find many knowledgeable and helpful people. Beware, there's a long post ahead.
To answer your question, different schools have different requirements. At some schools, primarily community colleges, the requirements for entry are minimal and your high school science courses generally satisfy them. Prerequisite courses like anatomy, physiology, microbiology, and chemistry are a taken in the first year of the program followed by nursing courses the second year.
At most four-year schools, students spend the first two years taking prerequisites, including those listed above, and the final two years taking only nursing courses.
Is your History degree a bachelor's or an associates?
Since you want a bachelor's degree, here are your choices:
If you have a bachelor's degree, you can complete the prerequisites and apply for an accelerated second-degree baccalaureate program. They generally range from 11 to 16 months and have a very competative admistions process. Some allow you to complete your bachelor's and masters in 3 years. Here is the link to programs nationwide:
http://www.aacn.nche.edu/APList.pdf
Alternatively, you can enter a traditional second-degree program which may or may not require you to complete the prerequisites prior to beginning (some of these programs incorporate the prerequisites into their curriculum). These take longer because you carry a lighter credit load.
If your history degree were an associates, then you would have to complete the prerequisites for the program prior to applying to the nursing program. You would apply as a traditional community/junior college transfer.
Remember, you can complete an associates in nursing and then complete a RN to BSN program. If you do it this way, you can work as a nurse while your job pays for you to get your BSN.
You could also work as a CNA (training is 8 to10 weeks I think) while your going to school, you will get some exposure to the clinical area and your job may pay for you to go to school part time. You could do an associates and then the RN to BSN.
Your state board of nursing should have a list of nursing schools. Take a look at the websites of the schools that interest you. They will have their prerequisites listed. What ever you do, either volunteer in a clinical setting or take the Certified Nurse Assistant course. Schools look favorably upon that.
Hope I didn't confuse you,
Wendy