[0:06]Cigarettes aren't good for us. That's hardly news. We've known about the dangers of smoking for decades. But how exactly do cigarettes harm us?
[0:16]Let's look at what happens as their ingredients make their way through our bodies, and how we benefit physically when we finally give up smoking.
[0:26]With each inhalation, smoke brings its more than 5,000 chemical substances into contact with the body's tissues.
[0:33]From the start, tar, a black, resinous material, begins to coat the teeth and gums, damaging tooth enamel, and eventually causing decay.
[0:44]Over time, smoke also damages nerve endings in the nose, causing loss of smell.
[0:50]Inside the airways and lungs, smoke increases the likelihood of infections, as well as chronic diseases, like bronchitis and emphysema.
[0:59]It does this by damaging the cilia, tiny hair-like structures whose job it is to keep the airways clean.
[1:07]It then fills the alveoli, tiny air sacs that enable the exchange of oxygen and carbon dioxide between the lungs and blood.
[1:15]A toxic gas called carbon monoxide crosses that membrane into the blood, binding to hemoglobin, and displacing the oxygen it would usually have transported around the body.
[1:26]That's one of the reasons smoking can lead to oxygen deprivation and shortness of breath.
[1:33]Within about 10 seconds, the bloodstream carries a stimulant called nicotine to the brain, triggering the release of dopamine and other neurotransmitters including endorphins, that create the pleasurable sensations, which makes smoking highly addictive.
[1:48]Nicotine and other chemicals from the cigarette simultaneously cause constriction of blood vessels and damage their delicate endothelial lining, restricting blood flow.
[1:57]These vascular effects lead to thickening of blood vessel walls and enhance blood platelet stickiness, increasing the likelihood that clots will form and trigger heart attacks and strokes.
[2:09]Many of the chemicals inside cigarettes can trigger dangerous mutations in the body's DNA that make cancers form.
[2:16]Additionally, ingredients like arsenic and nickel may disrupt the process of DNA repair, thus compromising the body's ability to fight many cancers.
[2:25]In fact, about one of every three cancer deaths in the United States is caused by smoking.
[2:32]And it's not just lung cancer, smoking can cause cancer in multiple tissues and organs, as well as damaged eyesight and weakened bones.
[2:41]It makes it harder for women to get pregnant and in men, it can cause erectile dysfunction.
[2:46]But for those who quit smoking, there's a huge positive upside with almost immediate and long-lasting physical benefits.
[2:53]Just 20 minutes after a smoker's final cigarette, their heart rate and blood pressure begin to return to normal.
[3:01]After 12 hours, carbon monoxide levels stabilize, increasing the blood's oxygen-carrying capacity.
[3:07]A day after ceasing, heart attack risk begins to decrease, as blood pressure and heart rates normalize.
[3:14]After two days, the nerve endings responsible for smell and taste start to recover.
[3:20]Lungs become healthier after about one month, with less coughing and shortness of breath.
[3:25]The delicate hair-like cilia in the airways and lungs start recovering within weeks and are restored after nine months, improving resistance to infection.
[3:35]By the one year anniversary of quitting, heart disease risk plummets to half, as blood vessel function improves.
[3:43]Five years in, the chance of a clot forming dramatically declines, and the risk of stroke continues to reduce.
[3:50]After 10 years, the chances of developing fatal lung cancer go down by 50%, probably because the body's ability to repair DNA is once again restored.
[4:00]Fifteen years in, the likelihood of developing coronary heart disease is essentially the same as that of a non-smoker.
[4:07]There's no point pretending this is all easy to achieve. Quitting can lead to anxiety and depression, resulting from nicotine withdrawal.
[4:16]But fortunately, such effects are usually temporary, and quitting is getting easier, thanks to a growing arsenal of tools.
[4:24]Nicotine replacement therapy through gum, skin patches, lozenges and sprays, may help wean smokers off cigarettes.
[4:34]They work by stimulating nicotine receptors in the brain, and thus preventing withdrawal symptoms without the addition of other harmful chemicals.
[4:41]Counseling and support groups, cognitive behavioral therapy and moderate intensity exercise also help smokers stay cigarette-free.
[4:50]That's good news, since quitting puts you and your body on the path back to health.
[4:57]If you want to see more videos on building healthy habits, check out this playlist.
[5:03]And if you want to help support TED-Ed's nonprofit mission, please consider making a small donation at patreon.com/teded.
