I am having trouble relating the Fick Principle to individual Organs and Body Systems. Please help!?

I need to correlate the Respiratory system, blood, and the heart in regards to the Fick Principle for a 5 page paper I am writing for my paramedic cl. I have a general understanding of the Principle and what is entails, but am having a difficult time of coming up with enough on each aspect to brainstorm and write the paper. Unfortunately my instructors did not discuss it very much past the 1/2 page handout they provided. I would greatly appreciate any words of wisdom or ideas from anyone. Thanks a lot.