What happens when you relapse with smoking? quit for roughly 5 years, then smoked for a few weeks. do your lungs and arteries go to back to the shape they were in prior to quitting for 5 years?

It will take some time for your system to recover. The length of time would depend on how long you smoked, give about one year for each week of smoking to return to baseline. You can reduce your risk of cancer by adopting healthy habits: Eat a mostly vegetarian diet, avoid alcohol, tobacco and street drugs, avoid excessive exposure to sun, maintain healthy weight, exercise 30 minutes/day.

For pulmonary system, most damages from long term smoking are not reversible or only partly reversible so if you smoke again the injury will progress from that baseline. However, if you only re-smoke for a very short time then quit, you less likely trigger another long lasting effect so you should be back to your shape 5 years ago.