12. Your Immune System
The barrage of toxins released into your body by smoking triggers your immune system to set off an inflammatory response. When your immune system is busy fighting off the effects of smoking, it becomes weakened. This makes it less effective in fighting off infections and other diseases you may come in contact with. Kick the habit and your immune system will be able to recover. You will notice an increased ability to fight off colds and other illnesses.
11. Your Brain
When smoking, the initial hit of nicotine that travels through your bloodstream causes dopamine to be released in your brain. Unfortunately, it only takes minutes for this quick burst of pleasure to wear off and jitteriness and agitation to replace it. While the addictive effects of nicotine on your brain are hard to overcome, when you stop smoking your brain is able to perform without the fluctuations of nicotine exposure and withdrawal. This can leave you calmer, clear-headed, and better able to focus.
10. Your Central Nervous System
Cigarettes have a profound effect on the levels of the neurotransmitters dopamine and serotonin in your central nervous system. The stimulant effects of nicotine and other components of cigarette smoke can leave you feeling agitated, jittery, and anxious. Others find that smoking is linked to depression. Memory and comprehension are also linked to dopamine and serotonin, so giving up cigarettes may improve your mental abilities and understanding.