Humans are the only species that have the "urge" to inhale harmful smoke into their body. Some smokers are casual smokers, who only smoke in a social scene other types of smokers who are depressed or stressed because they feel that it relieves something in them, and finally there are addictive smokers, who don't know why they even started but they can't stop. What these people don't realize is that the harm they are putting their bodies through. There are many risks of smoking like lung disease, heart disease, and risks in pregnancy to the unborn child. Today it is known that cigarette smoking is the leading cause of lung cancer and death in the United States. One researcher has described cigarette smoking as causing "a chronic inflammatory disorder of the lower airways."(Doll 901-911) .
When we breathe, air enters the upper airway through the nose and mouth where the air is filtered. The inhaled air travels though the trachea to the lungs. Inside the lung there is a main stem called the bronchus and little air sacs called bronchioles. Oxygen is exchanged for carbon dioxide in the blood. The blood then carries oxygen to all the body tissues. (Sherman 355) The respiratory system has several built in safeguards to protect it against disease. The filtering that takes place in the upper airway helps prevent infectious and irritating substances from entering the lung. The trachea and the lung produce mucus which helps trap and carry away contaminants. These contaminants are moved through the lungs by cilia which are tiny hairs that beat rapidly back and fourth. When smoke is inhaled through the mouth, smokers automatically bypass the first safeguard which is the filtering action of the nose. While smokers often produce more mucus in response to smoking they are le!.
ss able than nonsmokers to move the mucus out of their respiratory system. This happens because cigarette smoking paralyzes and will eventually destroy the cilia.