How the Human Respiratory System Works

Your respiratory system is dominated by your lungs. They bring fresh oxygen (O₂) into your body and expel carbon dioxide (CO₂). Oxygen travels from your lungs through the bloodstream to the cells in all parts of your body. Cells use the oxygen as fuel and give off carbon dioxide as 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 combination with your central nervous system, blood circulatory system, and your chest and diaphragm muscles.

In addition to gas exchange, your lungs and the other parts of your respiratory system have other important jobsrelated 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 or filtering them, or by alerting the body through your sense of smell.
• Defending the lungs with cilia (tiny hair-like structures) and mucus, which act to remove harmful substances deposited in the respiratory system.

How your health is affected

Lung tissue cells can be injured directly by air pollutants such as ground-level ozone, metals and free radicals. Ozone can damage the alveoli ― the individual air sacs in the lung where oxygen and carbon dioxide are exchanged.

Lung tissue has an abundant blood supply that can carry toxic substances and their metabolites to distant organs. In response to toxins, your 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 may also cause lung inflammation and impair lung function.

Particulates

Deposition of inhaled particles within the lungs varies widely depending on the particle size. Airway tissues that are rich in bioactivation enzymes can transform organic pollutants into reactive metabolites and cause secondary lung injury.

Larger (coarse) particles in air pollution are more likely to deposit in the upper airways of your lungs, and affect this part of your lungs. Smaller (fine) particles penetrate deeply into the alveolar region of the lungs and appear to be able to affect more basic lung function. These effects may be related to aspects of the chemistry or physical nature of the particles.

The human Respiratory system