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One of the hardest habits to break is smoking cigarettes. Everyone knows it damages the lungs, causing emphysema and cancer. But do people know HOW these illnesses occur on a physiological level? Perhaps if the mechanism were explained there would be more people quitting and fewer kids starting.

The two main ingredients of cigarette smoke are tar and nicotine. Simply put, tar is exactly what the word means. Tar is the thick, gooey black stuff that resembles the substance highway crews use in constructing roads. It is the residue (what is left) of tobacco after it has been smoked. It is in the smoker’s lungs.

Nicotine, on the other hand, is a chemical that is absorbed in the blood system and carried throughout the body. Nicotine is a vasoconstrictor, which means it makes the smoker’s blood vessels smaller in diameter for a while. This can wreak havoc on the heart, which has to pump harder when the vessels are in such a spasm. Nicotine is also what the smoker becomes addicted to.

The respiratory system, where the smoking takes place, begins at the mouth and nose. Down the throat and through the vocal cords lies the beautiful pulmonary structures. The trachea (windpipe) splits in two, becoming the right and left mainstem bronchiole tubes. Lined with hairlike structures called cilia, these tubes actually enter the lung tissue on both sides of the chest.

Like branches emerging from a tree trunk, the bronchiole tubes become smaller and smaller. Finally, the tiny tubes arrive at the alveoli, or air sacs. This is where gas exchange takes place. The blood cells drop the off carbon dioxide and pick up oxygen. It’s truly a wonderful relationship.

The effects of cigarette smoking disturb this balance within the lungs. Tar becomes deposited in the bronchiole tubes, plugging them up close to the air sacs. The lungs work to rid the tubes of tar by stimulating its owner to cough. Meanwhile, gas exchange is hampered because nicotine has constricted the blood vessels, pumping the blood too far away from the air sacs.

Some tar and other fluids eventually do make it up the bronchiole tree. This mucous will hopefully be carried toward the trachea. This relationship is called the mucociliary escalator. Unfortunately, nicotine paralyzes the cilia, making it harder for the lungs to get rid of the tar. The cilia usually come back to life by morning, ridding the lungs of debris with the morning cough. Continued smoking can permanently fry the cilia, thus impeding the clearance of tar.

When the lungs cannot clean out the tar, the air sacs can collapse. When the tar is moved out, the air sacs reinflate. After a while, the alveoli walls weaken and fuse into other alveoli walls. A dynamo effect takes place with alveoli fusing rampantly into one another. Instead of a healthy surface area from many alveoli, the surface area becomes compromised and markedly decreased. This decreased surface area jeopardizes gas exchange. This is emphysema. Once it starts, no one can stop it.

Breathing is so fundamental to life that to imperil the health of one’s lungs runs counter to common sense. To ignore the physiological changes that occur with cigarette smoking is like saying, “It can’t happen to me.” To hope that future generations will not notice the bad habits of the past is wishful thinking. Despite whatever method of denial used, infusing lungs with noxious fumes and chemicals can be terminally injurious to one’s health.