Cigarette smoking has steadily become less popular in the United States over time, with only 15 percent of adults now current smokers — a sharp decline from the 40 or so percent who regularly lit up in the 1960s.

We’ve been successful at curbing our sin stick habit, but thousands of new smokers, most often teenagers, are created every day. According to the Centers for Disease Control and Prevention, approximately 3,200 teens smoke their first cigarette every day, with about two-thirds going on to become regular smokers. Without any changes in smoking’s popularity, it’s likely that 1 of every 13 teenagers will someday die from a smoking-related illness.

In light of these alarming facts, let’s take a look at what happens to our body every time we decide to indulge in a smoke.

Brain Drain

The act of smoking introduces us to over 4,000 chemicals, many of these capable of subtly altering our body and brain within seconds.

For instance, nicotine shoots up to our brain via the bloodstream and triggers the release of dopamine, a neurotransmitter that plays a big role in making us feel pleasure. It’s this nearly instantaneous, but short-lived, effect that makes us addictive patsies to nicotine, as we begin to crave and eventually need more and more nicotine in order to experience the dopamine high again. What makes smoking especially dangerous is that the brains of teenagers are more vulnerable to nicotine, making them more likely to become hooked. Unfortunately for smokers, the high of nicotine also comes with a low that leaves them stressed out and agitated.

Nicotine doesn’t just temporarily make us feel good, though, it acts as a stimulant that prompts the release of adrenaline and causes our blood vessels to constrict, sending our blood pressure and heart rate into overdrive. These short-term effects on our cardiovascular system over enough time eventually lead to a long-known increased risk of cardiovascular disease, even without the smoke itself in the picture, and may also explais why long-time smokers often look older than their actual age.

Dirty Bodies

Of course, given that we breathe in cigarette smoke, it’s no surprise that its largest effects on the body involve our respiratory system.

When tar and other chemicals found in tobacco smoke are inhaled, they slow down the tiny microscopic hairs that line our lungs and windpipe called cilia. Immediately after and for hours later, these cilia have a harder time doing their necessary job of clearing out mucus and bacteria from where it isn’t wanted. That eventually leads to the telltale thick phlegm that smokers are notorious for hacking up regularly; it weakens our immune system; and prematurely ages our lungs. Tobacco smoke may also actively encourage infectious disease by making it easier for hardy drug-resistant superbugs to survive, and by subtly changing the types of normally harmless bacteria that call our bodies home.

Lastly, most of the chemicals found in smoke are carcinogenic, meaning that they can trigger minute changes in our cells that make them more likely to mutate out of control. The changes can take years to build up and cause cancer, but each cigarette you smoke just adds on to the pile.

Thankfully, many of these effects on the body are temporary and take a long time to become irreversible, meaning the sooner someone can successfully quit, the better off their health will be.

Read More:

Smoking Cigarettes: Most People Don’t Know Which Chemicals They’re Exhaling. Read here.

Why Can Some People Quit Smoking Cold Turkey? And Why You Probably Shouldn't Try It Yourself. Read here.