I was wondering if mris provide a full scan of the body even if its been ordered to follow up on a particular issue. for instance if the mri was ordered to look at bladder would it show upper body images also in the chest area, lungs, etc?

No. The ordering physician must order specific areas of the body to be studied. He/she has to list symptoms or the reason for the test or the insurance company or medicare will not pay for the study.

It is usually not the case that an MRI of entire body be performed to follow up one area in question. There are several reasons for this. MRI uses different types of pulse sequences, that can be optimal for one body part, but not for another. You want to maximize the visualization of that part you wish to see. Also MRI is not great for all body parts such as lungs.