Save The Earth , Save The Future

Structure and Function

The human respiratory system is dominated by our lungs, which bring fresh oxygen (O₂) into our bodies while expelling carbon dioxide (CO₂).  The oxygen travels from the lungs through the bloodstream to the cells in all parts of the body.  The cells use the oxygen as fuel and give off carbon dioxide as a waste gas.  The waste gas is carried by the bloodstream back to the lungs to be exhaled.

The lungs accomplish this vital process - called gas exchange - using an automatic and quickly adjusting control system.  This gas exchange process occurs in conjunction with the central nervous system (CNS), the circulatory system, and the musculature of the diaphragm and the chest.

The human respiratory system can be divided into the upper respiratory tract and the lower respiratory tract.  The upper respiratory tract includes the following rigid structures:

Nasal cavities: Filter the air we breathe and provide a sense of smell.

Pharynx: Acts in the respiratory and the digestive system.

Larynx: Link between the pharynx and the trachea.  Generates the voice with the presence of vocal folds.

Trachea: The trachea is the bond with the lower respiratory tract.  This is a flexible structure allowing the air to go down to the lungs.

In addition to gas exchange, the lungs and the other parts of the respiratory system have important jobs to do related to breathing.  These include:

• Bringing all air to the proper body temperature.
• Moisturizing the inhaled air for necessary humidity.
• Protecting the body from harmful substances by coughing, sneezing, filtering or swallowing them, or by alerting the body through the sense of smell.
• Defending the lungs with cilia (tiny hair-like structure), mucus and macrophages, which act to remove harmful substances deposited in the respiratory system

Human Respiratory System

The health of our lungs and entire respiratory system is affected by the quality of the air we breathe.  In addition to oxygen, this air contains other substances such as pollutants, which can be harmful.  Exposure to chemicals by inhalation can negatively affect our lungs and other organs in the body.  The respiratory system is particularly sensitive to air pollutants because much of it is made up of exposed membrane.  Lungs are anatomically structured to bring large quantities of air (on average, 400 million litres in a lifetime) into intimate contact with the blood system, to facilitate the delivery of oxygen.

Lung tissue cells can be injured directly by air pollutants such as ozone, metals and free radicals.  Ozone can damage the alveoli — the individual air sacs in the lung where oxygen and carbon dioxide are exchanged. More specifically, airway tissues which are rich in bioactivation enzymes can transform organic pollutants into reactive metabolites and cause secondary lung injury.  Lung tissue has an abundant blood supply that can carry toxic substances and their metabolites to distant organs.  In response to toxic insult, lung cells also release a variety of potent chemical mediators that may critically affect the function of other organs such as those of the cardiovascular system.  This response may also cause lung inflammation and impair lung function.

Cigarettes Contain Chemicals

1. Although the primary ingredient in cigarettes seems to be natural tobacco, a number of natural and synthetic chemicals are added to cigarettes to make them more appealing to smokers. According to chemists at the R.J. Reynolds Tobacco Co., cigarettes contain more than 4,000 chemicals, nearly four dozen of which are known carcinogens. Among the more prevalent chemicals in cigarettes are nicotine, formaldehyde, ammonia, arsenic, tar and phenylacetic acid.

Cigarette Smoke is Not Clean

2. While some of the chemicals found in cigarettes are burned off during the smoking process, many survive and even more are created. Arsenic and tar, for example, cannot be broken down by the heat of the cigarette; these chemicals are simply carried into the air as particulates in the cigarette’s smoke. The actual process of smoking, too, generates additional dangerous compounds such as carbon monoxide; the creation of these gasses further pollutes the air around a burning cigarette.

Cigarettes Release Pollutants

3. As a cigarette burns and its smoke is released, tiny particles of the more than 4,000 chemicals packed into the cigarette are released into the air. In addition, the smoke that is inhaled by the smoker can not be totally absorbed by the lungs, so it is released with small amounts of the original pollutants plus trace amounts of the smoker’s bodily fluids. As these particles float upward on the cigarette’s smoke, they dissipate into the surrounding air to produce pollution. Many of the particles and bodily fluids produced during the smoking process are short lived, so the greatest pollution effect is in the area immediately surrounding the smoker. Despite its limited spread, however, this pollution is acute. A 2004 study by Giovanni Invernizzi from the Tobacco Control Unit of Italy’s National Cancer Institute in Milan found that three burning cigarettes produced significantly more pollution than a running diesel car engine. The study was reported in the journal “New Scientist.”

With the destruction and burning of the rain forests more and more CO2 is being released into the atmosphere. Trees play an important role in producing oxygen from carbon dioxide. “A 115 year old Beech tree exposes about 200,000 leaves with a total surface to 1200 square meters. During the course of one sunny day such a tree inhales 9,400 liters of carbon dioxide to produce 12 kilograms of carbohydrate, thus liberating 9,400 liters of oxygen. Through this mechanism about 45,000 liters of air are regenerated which is sufficient for the respiration of 2 to 3 people”. (Breuer 1) This process is called photosynthesis which all plants go though but some yield more and some less oxygen. As long as no more wood is burnt than is reproduced by the forests, no change in atmospheric CO2 concentration will result.

Pollutants such as sulfur dioxide, nitrogen oxides, ozone and peroxyacl nitrates (PANs), cause direct damage to leaves of crop plants and trees when they enter leaf pores (stomates). Chronic exposure of leaves and needles to air pollutants can also break down the waxy coating that helps prevent excessive water loss and damage from diseases, pests, drought and frost. “In the midwestern United States crop losses of wheat, corn, soybeans, and peanuts from damage by ozone and acid deposition amount to about $5 billion a year”. (Miller 498)