American Medical Association Family Medical Guide - American Medical Association [24]
When you smoke, nicotine triggers the release of dopamine but prevents the brain from turning it off by blocking the release of acetylcholine. As a result, the brain continues pumping out dopamine, making you feel better and better. After nicotine levels in the bloodstream fall, dopamine production declines. The brain, recalling the good feelings, wants more, producing cravings for another cigarette. These processes take place inside a part of your brain that scientists call the reward center.
The brain’s reward center
Two structures—the nucleus accumbens and the ventral tegmental area—deep in the brain’s reward center are responsible for the release of dopamine, which produces feelings of pleasure.
When the brain’s reward center works normally
ON: The reward center releases dopamine to reward a good behavior, such as learning a new skill (green arrows).
OFF: Minutes later, another brain chemical, acetylcholine, shuts dopamine production off (red arrows).
When nicotine interferes with the reward center
ON: Nicotine in the bloodstream causes the reward center to release a flood of dopamine (green arrows).
NOT OFF: Nicotine blocks the release of acetylcholine, so the reward center keeps releasing dopamine until blood levels of nicotine fall, producing craving for more nicotine (red arrows).
Deaths from cigarette smoking
This chart uses figures from the Centers for Disease Control and Prevention to show the number and causes of deaths attributed to smoking each year in the US. Of the nearly half a million smoking-related deaths, 7 out of 10 result from lung disease, especially lung cancer and emphysema, and from heart disease and stroke.
How Smoking Affects the Lungs
Smoking is the major cause of lung cancer and emphysema (a chronic lung condition in which damage to the tiny air sacs in the lungs makes breathing difficult). Chronic inflammation of lung tissue from cigarette smoke and tar residue left by the smoke triggers a cascade of changes in cells in the lungs that can lead to cancer, emphysema, or both. In this cross section of a lung with cancer (top), the white area in the upper lobe is cancerous tissue, and the blackened areas are deposits of tar. The lung with emphysema (bottom) has multiple cavities (produced by the destruction of air sacs) that are surrounded by black deposits of tar.
Lung with cancer
Lung with emphysema
The Benefits of Quitting Smoking
Even if you’ve been smoking for years, when you quit, your body begins a series of changes to repair the damage caused by smoking and to restore health to affected cells and organs.
Time Since Last Cigarette Health Benefit
20 minutes Blood pressure decreases.
Pulse rate drops.
Circulation improves, making hands and feet feel warmer.
8 hours Breathing becomes easier because the amount of oxygen-depleting carbon monoxide in the blood decreases, which increases the amount of oxygen in the blood.
24 hours Risk of heart attack decreases.
48 hours Senses of smell and taste start to return.
Nerve endings begin to grow back.
2 weeks to 3 months Circulation continues to improve.
Walking gets easier.
Lung function increases.
1 to 9 months Symptoms such as coughing, sinus congestion, fatigue, and shortness of breath subside.
1 year Risk of heart disease is cut in half.
5 to 15 years Risk of heart disease is reduced to that of a person who has never smoked.
10 years Risk of lung cancer decreases up to 50 percent.
Risk of cancer of the mouth, throat, esophagus, bladder, kidneys, and pancreas drops.
15 years Risk of stroke decreases to that of a person who has never smoked.
Risk of dying of any smoking-related cause is nearly the same as that of a person who has never smoked.
How to quit