Yes. When you quit smoking you reverse the arterial damage caused by smoking and you start to reverse the immune damage caused by smoking. Some of the damage such as that is structurally to the lung that leads to emphysema was just started by smoking and carried on by your inflammatory system. That is not reversible and so is heart damage you have already suffered but many of the things caused by smoking are reversible.
In this video, Michael Roizen, MD, chief wellness officer for the Cleveland Clinic, explains how.