If nursing is your passion, keep your head up and try again! A&P is one of the most difficult pre-reqs because it is a lot of information, a lot of memorization, and a lot of concepts and body systems that you continue to build on (learn about). So if you don't understand something fully, its simple to get lost because things are so closely connected or intertwined. Best advice I can give is figure out how you learn best. Whatever you were doing obviously doesn't work, so try something new. Flash cards, online videos, read the book, have someone quiz you, pretend like your teaching the subject to others, study groups, read the chapter numerous times, find practice questions, record and listen to the lecture again, rewrite your notes, etc. Don't give up!!